The Porticus of Neptune is the monumental facade, along the Decumanus, of blocks III, IV (Baths of Neptune) and VI. Behind the facade are shops. It was built in the Hadrianic period. In front of the Baths of Neptune (II,IV,2) two rows of piers were added c. 350 AD, perhaps after an earthquake in 346 AD.
Reconstruction drawing of the central part of the portico,
seen from the south-east. From Calza 1914, Tav. V.