Welcome to the Baths of Agrippa! These baths were the first public baths in Rome and set the standard for the later series of increasingly extravagant and lavish imperial establishments.
The Baths of Agrippa were built on a low, wet area of the Campus Martius that was called in ancient times the "Goat's Marsh." This was the place according to Roman legend where Romulus disappeared in a sudden act of apotheosis in a thunderstorm. To build in this area Agrippa probably excavated the whole region and inserted a masonry frame creating a kind of dry dock in the marsh (model of baths and pool, the stagnum Agrippae).
Agrippa's original building on this site was called the "laconian sudatorium" and seems to have been a form of gymnasium. The actual baths were not established on the site until the completion of the Aqua Virgo, the aqueduct that fed the baths, in 19 BCE. The baths burned down in the great fire of 80 CE but were restored by Domitian (probably according to the original plan) and subsequently renovated in the time of Hadrian (second century CE) and Constantius and Constans (fourth century CE).