A huge lighthouse was built by Claudius between the two moles of his harbour. Ancient authors (Suetonius, Cassius Dio) tell us that the lighthouse was on top of an island, an isolated mole. They also state that part of the foundation of the lighthouse consisted of a huge ship, that had been used by Caligula to carry an obelisk from Egypt to Rome. Apparently it was used as a caisson. The building process must have been similar to that of the harbour at Centumcellae, not far away, during the reign of Trajan. It is described as follows by Pliny the Younger:

"I was delighted to be summoned by the Emperor [Trajanus] to act as his assessor at Centum Cellae [Civitavecchia], where I am now." [...] "The house is really beautiful: it is surrounded by green fields and faces the sea-shore, where a natural bay is being converted with all speed into a harbour. The left arm has already been reinforced by a solid mole and the right is in process of construction. At the entrance to the harbour an island is rising out of the water to act as a breakwater when the wind blows inland, and so give a safe passage to ships entering from either side. Its construction is well worth seeing. Huge stones are brought by large barges and thrown out one on top of another facing the harbour; their weight keeps them in position and the pile gradually rises in a sort of rampart. A hump of rocks can already be seen sticking up, which breaks the waves beating against it and tosses them high into the air with a resounding crash, so that the sea all round is white with foam. Later on piers will be built on the stone foundation, and as time goes on it will look like a natural island. The harbour will be called after its maker, and is in fact already known by his name; and it will save countless lives by providing a haven on this long stretch of harbourless coast."

The lighthouse was very high, and built after the example of the famous Pharos of Alexandria: altissimam turrem in exemplum Alexandrini Phari (Suetonius, Claudius XX), It could also be called Pharos, as could other lighthouses (see e.g. Herodianus IV,2,8). It is depicted on many mosaics in Ostia, on reliefs, sarcophagi and funerary slabs from Ostia and Rome, on coins of Antoninus Pius, Faustina and Commodus, on lamps and on the Tabula Peutingeriana.

The lighthouse of Alexandria on a coin of Domitianus.
Testaguzza 1970, p. 124.

According to Stuhlfauth the lighthouse probably had four storeys. The lower three were square or rectangular, the upper one was cylindrical. However, there are many variations in the depictions. A possible explanation for some of these variations is, that different sides of the lighthouse were depicted. Sometimes the lighthouse is depicted with a large arched porch in the lowest storey and with windows in the upper storeys, but sometimes all of the storeys have porches.

From lines on mosaics can be deduced that all storeys of the lighthouse were made of large stone blocks. There seems to have been a statue of an Emperor (Claudius or Nero?) on the penultimate storey. On top burned a fire to guide ships during the night. Pliny the Elder explains that "the danger lies in the uninterrupted burning of the beacon, in case it should be mistaken for a star, the appearance of the fire from a distance being similar" (periculum in continuatione ignium, ne sidus existimeretur, quoniam e longinquo similis flammarum aspectus est; NH XXXVI,xviii,83).

Taking the fuel for the fire to the top must he been a particular challenge. Sloping ramps inside the lighthouse may have been used, as in Alexandria. This takes us to the interior of the lighthouse. The ancient depictions suggest that the lighthouse was quite wide and had many storeys (in contrast to the lighthouse in Alexandria, which had only a few storeys and was relatively slender). Each upper storey seems to have been considerably narrower than the storey below. This is a very unusual shape for a tower, and I do not know any parallels. How was the weight of each upper storey handled? The shape of the lighthouse is as unusual as the shape of the Trajanic hexagonal basin.

The ancient authors do not tell us how high the lighthouse was. Some archeologists believe that the lighthouse in Alexandria was 120 metres high (with a foundation of 30x30 metres), and there is no reason to think that the lighthouse of Portus was lower. If it was 50 metres high it could be seen in Rome - and it surely could. If it was 120 metres high (23 metres higher than Big Ben) it could be seen at a distance of 40 kilometres. Claudius may well have decided to make the lighthouse of Portus slightly higher than that of Alexandria, to underline the supremacy of Rome. Similarly the sinking of the ship that had been used for the transport of an obelisk may not only have been a technical operation, but also a symbolical deed (Boyce 1958, p. 77). The lighthouse seems to have been restored by Antoninus Pius: Phari restitutio (SHA 8, 2-3; the context suggests that the lighthouse of Portus is meant, because it is mentioned in a list of work that took place in Italy only).

In the period 334-345 AD Lucius Crepereius Madalianus is consul(aris) molium phari at(que) purgaturae, i.e. responsible for the maintenance of the moles and the lighthouse, and for dredging in the harbour. This is what we read in an inscription that was found near the hexagon by Guido Calza (Calza 1925; Thylander B336). This, by the way, is the inscription from which has been deduced that Constantine made Portus a city that was independent of Ostia:

FID(a)E EXERCITATIONEM BONITATI POLLENTI LVCIO CREPEREIO MADALIANO V(iro) C(larissimo) PRAEF(ecto) ANN(onae) CVM IVRE GLADII COMITI FLAVIALI CORR(ectori) FLAM(iniae) ET PICENI LEG(ato) PRO PRAETORE PROV(inciae) ASIAE LEG(ato) PROV(inciae) AFRICAE CONSVLA(ri) AED(ium) SACRAR(um) CONSVL(ari) MOLIVM PHARI AT(que) PVRGATVRAE QUAEST(ori) CANDID(ato) PRAET(ori) CONSVLI OB MVLTA IN SE EIVS TESTIMONIA ORDO ET POPVLVS (civitatis) FL(aviae) CONSTANTINIANAE PORTVENSES STATVAM PVBLICAE PONENDVM CENSVERVNT

The Codex Theodosianus (XIV.6.3.1-8) mentions the lighthouse in 365 AD. In late antiquity the lighthouse was used as a symbol of salvation on Christian sarcophagi.

Documents from 1018 and 1049 mention two towers in Portus, presumably the Claudian and Trajanic lighthouses. One is called Cocuzina or Cucuzuba / Cucuzuta, the other Molon or Montone. We also hear of a fundus Bacatus, a name apparently derived from the Claudian lighthouse (Baccha = Specula = Pharus). On August 25, 1190 Richard Coeur de Lion visited Ostia, and we hear this: Et postea intravit Tyberim; ad cuius introitum est turris pulcerrima sed solitaria ("And after that he entered the mouth of the Tiber, at the entrance of which is a very beautiful but solitary tower"). Meiggs suggests that he saw Tor Boacciana, which was perhaps a small lighthouse at the mouth of the Ostian branch of the Tiber. But can that simple tower really be called a very beautiful tower, or was this the lighthouse of Portus? Remains of the lighthouse could still be seen in the 15th century. In the book De Roma instaurata, written 1444-1446, Flavio Biondo wrote: "Di questa torre ne veggiamo, insino ad hoggi una buona parte in pie, se non che ne sono stati tolti i marmi, de quali ella era incrustata" (translation by Lucio Fauno, Venezia 1558, 41). Note that according to Flavio Biondo the tower was decorated with marble. In his Commentaria rerum memorabilium Pius II Piccolomini (died 1464) wrote: "Ancora rimangono vestigia della torre le quali si vedano là nel mare; tutti gli altri monumenti sono periti interamente" (edition Frankfurt 1614, 301). In 1483 Sixtus IV (Francesco della Rovere) visited Portus "dove si vedono ancora i muri vetustissimi della città di Porto, molto diruti, e la torre del Faro, tanto che ancora oggi essa conserva lo stesso nome" (Iacopo Gherardi, Il Diario di Roma, in Muratori, Rerum Italicarum Scriptores Vol. 23, part 3, 3-4). After 1483 there are no further references to the lighthouse. Perhaps the last remains were demolished soon afterwards.

The exact location of the lighthouse is known and will be published soon.

Ancient depictions of the lighthouse:

Mosaic in the House of the Harbour Mosaic (I,XIV,2).

Mosaic in statio 3 on the Square of the Corporations (II,VII,4).

Mosaic in statio 22 on the Square of the Corporations (II,VII,4).

Mosaic in statio 23 on the Square of the Corporations (II,VII,4).

Mosaic in statio 26 on the Square of the Corporations (II,VII,4).

Mosaic in statio 35 on the Square of the Corporations (II,VII,4).

Mosaic in statio 46 on the Square of the Corporations (II,VII,4).

Mosaic in statio 49 on the Square of the Corporations (II,VII,4).

Mosaic in the Baths of the Lighthouse (IV,II,1).

Mosaic in the Isola Sacra necropolis, tomb 43.

Mosaic in the Imperial Palace of Ostia, courtyard 73.

Relief of a ship approaching the lighthouse.

Relief on a sarcophagus of a ship approaching the lighthouse, from the Isola Sacra necropolis, tomb 90.

Relief of the lighthouse, on the Torlonia Relief, from Portus. Also a female figure with the lighthouse on her head in the upper left corner.

Relief of the lighthouse on a travertine block, probably from a tomb to the south of Ostia, now outside the museum in Ostia. Photograph: Giovanni Lattanzi, www.archart.it. Reproduced with permission.

Graffito from Ostia.

Graffito from Ostia.

Graffito from Ostia (next to Trajan's column).

Painting from the so-called Capitaneria in the harbour of Claudius: two masks of winds flanking the lighthouse (Testaguzza 1970, p. 125).

Coin of Antoninus Pius, with depictions of a grain measure, Annona (personification of the grain supply) holding a tessera frumentaria and a rudder, and the lighthouse. Text: ANNONA AVG FELIX SC (Meiggs 1973, Pl. XVIII).

Coin of Commodus, with depictions of ships (one with Jupiter Serapis), two men sacrificing (one of which is the Emperor), and the lighthouse. Text: VOTIS FELICIBVS (Meiggs 1973, Pl. XVIII).

Funerary slabs with depictions of the lighthouse (Stuhlfauth 1938, figs. 5, 6, 7).

Drawing of the lighthouse on the Tabula Peutingeriana.