1 Internal mole. 2 Claudian portico. 3 Harbour for smaller boats (so-called "Darsena"). 4 Porticus Placidiana. 5 Small lighthouse. 6 Baths. 7 Small theatre. 8 "Imperial palace". 9 City wall. 10 Colossal statue of Trajan. 11 Temple of Liber Pater. 12 Villa Torlonia. 13 Aqueduct. 14 "Temple of Portumnus". 15 Defensive cross-wall with towers. 16 Horrea. 17 Barracks of the fire-brigade? 18 Bishop's palace. 19 Tower. 20 Temple. 21 Church of St. Peter and St. Paul. 22 Foro Olitorio. 23 Grandi Magazzini di Traiano. 24 Grandi magazzini di Settimio Severo.

After R. Meiggs, Roman Ostia, Oxford 1973, figs. 5 and 6, with additions and modifications.