The Roman Bath was built in the mid-second century AD. Archaeological remains have shown that the bath continued in use until its abandonment in the late fourth century AD, after which it fell into decay and finally collapsed in the late sixth century. Pottery, walls, hearths, and cement floors suggest activities continued in this area during the Byzantine seventh and eighth centuries.
The Roman Bath at Isthmia
The Roman Bath was an elaborate structure, with vaulted ceilings, numerous sculptures, and marble dressed walls; however, the most dominating feature in the Roman Bath area is the Italian style monochrome mosaic found in room VI. The mosaic, accompanied by the colossal statue bases and remnants of sculpture, clearly identifies room VI as the great hall of the Roman Bath complex.
Bathing in Roman times was a lengthy and social event, lasting several hours and involving a trip through most of complex, including both the caldarium and frigidarium. The bather would have entered the bath through either rooms I or XII, and changed in rooms I, II or VII. Individuals using the bath could then have proceeded into room VI, the mosaic room. This was the main gathering hall of the structure, and this is where a majority of conversation and socializing would have taken place.
Central panel of monochrome mosaic in room VI
The mosaic consisted of many small black and white tesserae which, when placed together in the correct order, formed many different designs. The eastern and western thirds of the mosaic are decorated with geometric patterns and the border of the mosaic is composed of square and rectangular panels containing dolphins, flowers, and crosslets; the large central panels are mirror-images of themselves, depicting Tritons with Nereids on their backs, surrounded by various sea creatures. This is the largest monochrome mosaic in the eastern Mediterranean, measuring approximately 20 meters by 8 meters.
The rest of the bath, was actually used for bathing purposes. The frigidarium (rooms III-V) held cool plunge pools. The caldarium (rooms IX,XI, and XIII) were heated rooms with warm pools. Room X served as a heat-lock between the caldarium and frigidarium, a kind of "warm room" between these two sections of the bath complex. These heated rooms were each warmed by one or more furnaces, and a sophisticated system of hypocausts supported their floors. The hypocausts were made of piers of stacked clay disks (approximately .30m in diameter) that were stacked one-and-a-half meters high, and were covered with mortar, large square tiles, and nicely cut marble slabs, forming the floor of these rooms. Furnaces were located to the south of Rooms IX and XI, west of Room XIII, and north of Room X. From these furnaces, the hypocausts were sufficiently warmed to heat up the entire room above. The smoke escaped through numerous flues in the wall, providing effective heating for the whole room.
Plan of Roman Bath
The Roman Bath at Isthmia required enormous quantities of fresh water for its use. There was an ample supply of water in the vicinity, located several hundred meters to the southwest. Presumably, the water was brought to the Bath by aqueduct, but no trace of these has been found. The water may have been stored in tanks, perhaps even on the roof of the building, and one or more reservoirs discovered on higher ground south of the Bath may also have stored water for it.
In addition to a readily available water supply, a sophisticated drainage system is also a necessary part of any working bath. Horizontal drains, constructed of large rectangular blocks and covered with waterproof cement, were found in Rooms I, III, VI, and IX, all emptying into a vertical drain in the southwest corner of Room II. In several modern experiments, the drains still worked sufficiently after 2000 years. The drains in the Roman Baths at Isthmia were kept clear until AD 400 when they became filled with objects such as coins and pottery, both of which are used by archaeologists to date the clogging of the drain.
The Roman Bath was built over a Greek structure of a similar nature; and the restoration of the monochrome mosaic in room VI allowed for a closer inspection of the Greek pool, partially located beneath the area of the mosaic.