Below Via dei Vigili, to the south-east of the Barracks of the Fire Brigade, remains were found of baths. They have been dated to c. 50 AD, that is shortly after Ostia received its first aqueduct. Of great interest is a black-and-white mosaic (13 x 9 metres).
Drawing of the mosaic. From NSc 1912, p. 207.
In the centre are four dolphins, referring to the sea. To the right of the dolphins are two male, winged heads, one bearded and one unbearded. These represent winds. Two other heads represent provinces. A female head with a wreath of olive is the personification of Spain. The triskeles (three legs) is the symbol of Sicily. To the left of the dolphins are two more winds, and two more provinces. A female head with a crocodile-head is the personification of Egypt. A female head with an elephant's head and tusks refers to Africa. Shields and spears refer to the conquering of the provinces.
The mosaic is most likely related to the building of the harbour of Claudius at Portus: the city of Rome relied on Sicily, Egypt and Africa for most of its grain; Spain was a major oil-exporting province.