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Cassius Dio (53.27.1), who wrote in Greek, described among a number of Agrippa monuments the “stoa of Poseidon” built in 25 BC.  This structure was destroyed in the fire of Titus in AD 80 (Cass. Dio 66.24.2). The structure that is attached to this name is the Hadrianic-era monument just south of the Pantheon, fitting the area described by Cassius Dio, between the Pantheon and Baths of Agrippa.  The preserved interior marble decoration includes a frieze of dolphins and tridents, fitting for the “Basilica of Neptune” theme and possibly an allusion to Agrippa’s original naval battle conquests against Sextus Pompey and the battle of Actium. The structure was much larger than the narrow portion currently revealed through excavation. It is estimated to have been 46 meters  X 19 meters.

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From Platner & Ashby’s (1929) Topographical Dictionary of Ancient Rome:

Basilica Neptuni:  a building restored by Hadrian  and mentioned in Cur. in Region IX and in Pol. Silv.  This basilica is now generally, and properly, identified with the στόα Ποσειδῶνος built by Agrippa in 25 B.C.  and with the Ποσειδώνιον that was burned in the great fire in the reign of Titus and stood between the Pantheon  and the Hadrianeum. By some it has also been identified with the Porticus Argonautarum (q.v.) but it is probable that they were separate structures, although near together and possibly adjoining (Lucas, Zur Geschichte der Neptunsbasilika, Berlin 1904; OJ 1912, 132‑135). 

Where in Rome is the Basilica of Neptune?

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Cite this page as: Darius Arya, The American Institute for Roman Culture, “Basilica Neptuni (Basilica of Neptune)” Ancient Rome Live. Last modified 11/11/2019.


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