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The mills-bakeries of Ostia and the distributions of free grain

Jan Theo Bakker


Each archaeologist studying Ostia is acutely aware that the ruins represent the situation in late antiquity and the early Middle Ages. This situation was in great contrast with the developments in the second century, when Ostia was flourishing like never before or after.

During its heyday Ostia must have had some 40.000 inhabitants (depending on the number of floors one wishes to reconstruct). In the third century - a period of deep crises - this number must have decreased considerably. Commercial buildings along the Tiber and spacious apartments elsewhere in town were abandoned and left to collapse. The commercial emphasis shifted to Portus, which was Ostia's harbour district, situated a few kilometres to the north. Portus even became an independent city from the reign of Constantine. This however was not the end of Ostia. The city became a pleasant seaside living environment. Several commercial buildings were modified drastically and changed into wealthy habitations. In the early fifth century the final decline did set in. Buildings were looted, marble was taken to lime ovens, and metal objects were melted down. Flimsy walls, found and often removed by the excavators who worked in the first half of the 20th century, testify to impoverished habitations.

Obviously then the number of bakeries that can be recognised today is much smaller than the total during Ostia's golden age. When the population shrunk, the number of bakeries was reduced accordingly. The discarded bakeries were sometimes reused for other purposes, and sometimes left as they were. It should also be remembered that only some two-thirds of the city have been excavated.

The appearance of the mills-bakeries

Roman bakeries were usually mills-bakeries. Only in later antiquity can we make a distinction between the milling and baking, namely after the introduction of water mills, such as have been found on a steep slope of the Ianiculum in Rome and near Arles (the Barbegal). Until the mid-1980's two of these mills-bakeries had been identified in Ostia: the House with the Millstones (I,III,1), to the east of the well-known House of Diana, and Mill I,XIII,4, in the south part of town.

A Dutch team studying the bakeries was then able to identify five or six more. One of these establishments, near the museum, has disappeared completely, and is known only from the excavation diaries. The identification of Building II,VIII,9, to the east of the Great Warehouse (II,IX,7), remains uncertain. Only the south part of the building has been unearthed, and further excavation may show whether it was indeed a bakery. No doubts remain about the function of the House with the Ovens (II,VI,7), House I,IX,2, the House with the Wooden Balcony (I,II,2.6), and finally the House with the Cistern (I,XII,4). [Click here to open a map with the bakeries in a new window]

All of these bakeries have a lot in common, and the technical achievement was quite considerable. The workshops are quite large, and cover a ground floor area ranging from 640 to 1525 square meters. On average the bakeries contained nine millstones.

Reconstruction drawing of a millstone.
From Adam 1984, fig. 735.

A millstone consisted of two parts: an immobile, conical base (meta) and on top of that a stone that was shaped like an hour-glass (catillus). Mules or horses were attached to a wooden frame over the catillus. They walked in circles and rotated the catillus over the meta. The grinding took place between the two parts, that were at a very small, fixed distance. If the distance was too small, the grain would have been burnt, and if it was too large, too much bran would have remained. Specialist carpenters maintained the machines. Many of their tools were actually found in the House with the Millstones, where they also had a small workshop, the shop-sign of which can still be seen in the east facade. Inside the millstone dosage cones were used.

Drawing of a dosage cone (left) and of the use (right).
From Baatz 1994, fig. 20,12 and fig. 14.

Machines were also used for the kneading. Like the millstones they were made of porous volcanic stone. They are bowls in which the dough was kneaded by a combination of fixed and rotating blades. A few blades were inserted in the side of the bowl, and a few were attached to a vertical bar. Slaves or animals turned the vertical bar.

Cross-section of a kneading-machine.
From Blümner 1912, fig. 26, p. 65.

Huge, well-ventilated halls were built for the machinery. Often the first floor formed part of the workshop as well. Grain was led from there to the millstones through wooden pipes. The floors suffered a lot, and were therefore covered with basalt blocks, in which imprints of hooves remain. Many basins are found, because water was needed in very large quantities, for the kneading, as drinking water for the animals, for moistening the grain before milling and so on. The bread was baked in huge ovens, consisting of a base with a cupola, that had an inside diameter of 3.5 to 5 meters. Wood was burned inside the cupola, as in modern pizza ovens. The ovens could contain rotating grates on which the bread was placed.

A marble block in which ollae were inserted, found in Ostia, now in the Vatican.
It was made by P. Nonius Zethus, Aug(ustalis), for himself,
the freedwoman Nonia Hilara and his wife Nonia Pelagia.
To the left and right of the inscription the interior of a bakery is depicted.
First century AD. CIL XIV, 393.
Photograph: Bill Storage.

Detail of the relief on the block: a millstone.
Cast, Museo della Civiltà Romana. Photograph: Jan Theo Bakker.

Detail of the relief on the block: various objects used in a bakery.
Cast, Museo della Civiltà Romana. Photograph: Jan Theo Bakker.

The Ostian bakeries may be called factories, especially when they are compared to their counterparts in Pompeii. The latter contained only three to four millstones, very close to each other. The spacious Ostian bakeries must have been operated in a much more efficient way and more hours per day. However, waterpower was not used for the milling in Ostia. Many water wheels have been found in the city, but they all supplied baths. Rough and admittedly tentative estimates can be made of the production capacity of the millstones. A millstone in Pompeii must have supplied some 90 people, if it is true that the city had approximately 10.000 inhabitants. A water-powered millstone could serve between 320 and 690 people. An Ostian millstone may have produced flour for some 150 to 300 people. This means that, in the second century, there must have been approximately 178 millstones in at least 20 bakeries. In the identified bakeries must have been 60 to 65 millstones.

The Sanctuary of Silvanus

For the study of the bakers' trade in Ostia we possess various other sources, that are quite informative: reliefs, inscriptions, legal texts, and in particular a shrine with wall paintings and graffiti. This shrine is a narrow and dark room in the back part of the House with the Millstones. It could only be entered by passing through the entire bakery.

It was excavated partly in 1870, when fifty bronze and silver statuettes were found. Unfortunately many of these were stolen during the excavation, and we do not know which deities they represented. The bakery and the shrine were excavated completely from 1913 to 1916. It became clear that the bakery had been destroyed by fire and had not been rebuilt (coins and the masonry suggest that the fire occurred at the end of the third century). As a result, many objects were unearthed. Some were related to the workshop, such as parts of horse harnesses, bells that rang when the hopper was empty, and metal parts of dosage cones for the millstones. Other finds were related to surprisingly wealthy habitations on the upper floors - bronze revetment of furniture, sometimes with silver inlay, marble and terracotta friezes, fragments of black-and-white mosaic floors and of painted ceilings, tiny columns, marble revetment, and so on.

After the 1870-excavations only a few objects were found in the shrine, but on the walls many paintings were found of people and deities. Most of the figures were identified correctly by the excavator, Guido Calza, but the relationship with the bakery had to our surprise never been investigated.

The main deity in the shrine was Silvanus, a god of the woods. The room was therefore called "Sanctuary of Silvanus" by the excavators. Silvanus was depicted next to the entrance, on the outer wall. He was also painted in the back part of the room, on the right wall. The latter painting, which is now in the museum of Ostia, once had a painted text, stating that it had been made after a vision: Silvanus had appeared to one of the bakers in a dream.

Next to Silvanus one can still read the following graffito: "Calpurnius, night-watchman from the group of lieutenant Ostiensis, from the seventh cohort, during the reign of Caracalla and the consulate of Laetus and Cerialis [215 AD], X". Calpurnius, a fire fighter from Rome, stationed in Ostia, patrolled through the city at night with a torch. "X" means that he prayed for "ten more years for Caracalla", as the Americans would say today. On the opposite wall Calpurnius scratched the exact day on which he visited the shrine: April 25 (probably because on that day the Robigalia were celebrated, in honour of the god Robigus, for the prevention of the rust disease in grain).

Graffiti of night-watchmen have also been found in barracks in Rome, in Trastevere. Their work in the sparsely lit streets was quite dangerous, as can be deduced from texts such as "All was safe", and the apparent need for support by the divine Emperors.

Portrait of Caracalla in the Capitoline Museums.
Photograph: Jan Theo Bakker.

A thin wooden partition wall created an anteroom. Here some horses and the Dioscures were depicted. In the shrine proper is an altar, in front of some niches. On the floor is a black-and-white mosaic of a person who is about to kill a sacrificial animal. Parallels for this figure are found in the shrine for the Imperial cult in the Barracks of the Fire Brigade.

On the right wall, next to Silvanus, are the scanty remains of a figure with a lance or sceptre. On the left wall we see a whole row of figures: Augustus, Harpocrates, Isis, Fortuna, Annona, a figure with a cornucopiae (a Genius? Serapis?) and Alexander the Great. From the location of Calpurnius' second graffito can be deduced that all these figures had been painted before April 25, 215 AD. They are to be understood as follows. Augustus and Alexander the Great are present as illustrious predecessors of the Emperor, Caracalla, son of Septimius Severus. In 214 AD, at the age of 26, he had left for Egypt. During his journey he was overcome by an Alexander-mania, which several ancient historians have described. He ordered that throughout the Empire depictions should be made that presented him as a new Alexander. The Ostian bakers obeyed. They also thanked the Emperor for his distributions of free grain, personified by Annona. Isis (here, as so often, associated with Fortuna) and the child-god Harpocrates refer to the large quantities of grain that were imported from Egypt, which was an Imperial domain. The Dioscures were worshipped in Ostia as protectors of shipping, in this shrine as protectors of the grain fleet that transported the grain from Alexandria to Ostia and Portus.

Distributions of free grain

Does the presence of Annona in the shrine point to distributions of free grain in Ostia, or is it merely a reference to the well-known distributions in Rome? Each month 150.000 to 200.000 inhabitants of Rome received five measures of grain, a gift by the Emperor. This was not a system of relief for the poor, but a way for the Emperor to strengthen his ties with the populace. So far few historians have wondered how bread was made of this grain. It seems out of the question however that the recipients, often living in rented apartments, made their own bread, if only because of the fire hazard. The recipients could of course have made their own arrangements with bakers or people operating ovens, but this does not seem to have been the case. The Dutch legal scholar Sirks, member of the team, has shown that the Emperor entered into contracts with bakers for this purpose. The bread in Juvenalis' famous sneer "bread and circuses" (Satires X, 81) is to be taken literally, it is not a poetic description of grain: the Emperor did not leave the milling or baking to the recipients of free grain.

Originally the Emperor had to draw up contracts with individual bakers, such as M. Vergilius Eurysaces, whose enigmatic tomb - in my view quite possibly a folly - can still be seen outside the Porta Maggiore in Rome. Trajan simplified the system and devised a body or guild (corpus) of bakers in Rome, with which he did business. From now on a single contract sufficed. Membership was not compulsory. The Emperor just needed enough members for his own purposes: the feeding of his slaves and personnel, and of the fixed number of recipients of free grain.

The grain was taken to warehouses owned by the Emperor - either by the recipients themselves or by porters -, and here the bakers collected it. The recipients paid a baker a fixed amount for the milling and baking, but nothing for the grain. In other words: they received cheap bread, rather than free grain. Arrangements must also have been made for the Imperial slaves, and we know that the Imperial fire fighters received free grain as well.

Ostia is the only city other than Rome in the western half of the empire in which a bakers' guild is documented. It was probably instituted during Trajan's reign. During the reign of Commodus the prefect of the grain supply, residing in Rome, bestowed favours upon it. Many Imperial slaves worked in the harbour, and fire fighters from Rome were stationed in the Barracks of the Fire Brigade (our Calpurnius was one of them). It seems most likely that the Ostian guild baked bread for these people, on the basis of contracts with the Emperor. But did Ostia have distributions of free grain as well? The study of the bakeries by the Dutch team provided some answers.

The dates and distribution of the bakeries

More than half of the buildings in Ostia were erected during the reign of Hadrian, shortly after the completion of Trajan's harbour. In this period many bakeries must have been built, but of the identified bakeries only one (Mill I,XIII,4) can be assigned to it. The other workshops were installed at various points in time from the reign of Antoninus Pius to the Severan period, that is, during the next 100 years. Often Hadrianic buildings were altered for the purpose. This is a most surprising development. For example, the House with the Ovens is situated to the west of the Barracks of the Fire Brigade and most likely served the fire fighters. The Barracks were built under Hadrian, but the bakery was installed later, during the reign of his successor, in Hadrianic shops. Apparently the bread for the fire fighters was originally prepared elsewhere in town.

Equally surprising is the distribution of the bakeries. There is a concentration in the centre of town, especially to the east of the Forum. Exceptions are the House with the Ovens, the position of which was probably dictated by the Barracks, and Mill I,XIII,4, the only bakery from the early second century. Why were so many bakeries - noisy workshops, where slaves and convicted criminals toiled in flour dust - located and tolerated near the representative and monumental centre of town? Two bakeries even flank the Decumanus Maximus, a clear disfigurement of Ostia's main street. It causes little surprise that this situation was corrected much later, when these two bakeries had been abandoned: a large, decorative apse and a nymphaeum were then installed in rooms along the Decumanus. [Click here to open a map of the city centre with the bakeries in a new window]

The Great Warehouse

The explanation for the distribution is found quickly. The bakeries in the centre of town are near the Great Warehouse, one of Ostia's largest warehouses for grain. We seem to witness rationalisation, economic simplification of the bakers' trade. Apparently it was more practical or cheaper if the bakeries were situated near their main raw material. The building dates back to the reign of Claudius and Nero. It was rebuilt and extended during the reign of Commodus and the Severan Emperors. Eventually it could hold between 5.660 and 6.960 tons of grain, enough to feed at least 14.000 people for one year. The exceptional importance of the building is indicated by the name of the street to the west - the only street in Ostia of which the ancient name is known. In a city full of warehouses it is significant that precisely this street was called Semita Horreorum, i.e. Crossroad of the Warehouse.

This road started near the Tiber, ran between the House with the Millstones and the Great Warehouse, and continued towards the south, along the east side of Mill I,XIII,4. The latter bakery, with its exceptional date and location, is in this way connected with the cluster of bakeries.

After the reign of Hadrian one bakery after the other was installed near the Great Warehouse: the House with the Wooden Balcony, the House with the Cistern, a bakery near the museum, the House with the Millstones, and perhaps a bakery to the east of the warehouse. The warehouse probably also supplied Mill I,XIII,4 and the House with the Ovens (another large is situated near the latter bakery, but was built only after its installation). Some 54 millstones may have been filled with grain from the Great Warehouse. If our suggestion is correct that an Ostian millstone produced flour for approximately 225 people, then the total production would have been sufficient for some 12.000 inhabitants.

The size, quality and complexity of the Great Warehouse suggested to Rickman that it was Imperial property. The investigation of the House with the Millstones confirmed this idea. This bakery - the one with the shrine where Caracalla was thanked - had a direct connection with the warehouse, through a roof over the Semita Horreorum. A further argument is the tremendous size of the original warehouse. In the first century Ostia had few high-rising buildings, and must have been similar to Pompeii. The colossal building must have made quite an impression. It seems to have been built very consciously near the Forum, thus stressing the generosity of the Emperor.

The bakeries that were supplied by the warehouse must have been owned by members of the Ostian bakers' guild. The date of installation of the bakeries presumably reflects the enrolment of new members over an extended period of time.

Distributions of free grain in Ostia?

There are good reasons to think that the members of the Ostian bakers' guild did not just bake bread for Imperial slaves and personnel. They seem to have worked for recipients of free grain as well. The location of the Great Warehouse and the dependent bakeries simply cannot be understood if we suppose that these buildings supplied only Imperial slaves and a few hundred fire fighters. The bakeries swept over the area near the Great Warehouse like a dark cloud. We already mentioned the disfigurement of the Decumanus. The nature of the area between the House with the Millstones and the Capitolium changed dramatically. To the north-east of the temple a block with a large mansion, several attractive rented apartments and a large garden had been built (I,IV). The mansion was now converted to a hotel annex brothel. In the north part of the garden a warehouse with large vessels for oil was installed. Bars and a restaurant were built along the road connecting the Great Warehouse and the temple. Many examples can be found in Ostia of the profound influence of workshops and other commercial buildings on the cityscape, but nowhere is this influence as strong as here, the result of the Imperial involvement.

We should also note that Mill I,XIII,4, on the Crossroad of the Warehouse, is situated in the south part of town, far from the harbour district, where the Imperial slaves worked. Finally the supposed number of people served by the bakeries (12.000 to 14.000) implies an extremely high number of Imperial slaves in Ostia. Perhaps one-third of the population of Ostia consisted of slaves, as in Rome, that is some 13.000. However, many of these were not owned by the Emperor.

The presumed distributions may have been started by Claudius, who spent a lot of time in Ostia, was responsible for the first harbour at Portus, and during whose reign the Great Warehouse was built.

The final publication of the Dutch team included a full description and analysis of three Ostian bakeries. The remaining workshops were studied in a concise manner. It is our hope that others will take up our work, compile detailed catalogues of the remaining bakeries, and verify our conclusions

Small millstones, stored in the Piccolo Mercato. Photograph: Jan Theo Bakker.

This is the text of a lecture held for the Classical Association at Durham, UK, on Friday 5th May 2000. It was reworked for Descoeudres 2001, and published in French.