When works on a ventilation shaft for the Athens metro in the 1990s revealed these important finds, the shaft was moved to another location and the baths were excavated to reveal part of their now faded glory.
The ancient Ilissos River once ran into the baths, which covered a much larger area and contain many chambers. They were built in the third century AD after the Herulian raids had destroyed the city, and were enlarged in the 5th or 6th century AD. Evidence shows that there were two heating spaces or praefurnia, nine chambers, and several hypocausts (ancient Roman underfloor heating systems to heat spaces with hot air).
The large jugs seen today were clay silos for storing cereals, brought in by the Byzantine civilization (i.e. after the Roman civilization). The rest of this complex lies under the gardens and Amalias Avenue, so this must be seen as just a glimpse of what was once a mighty Roman bathhouse with a sophisticated system that the Romans once lavished in.