The Byzantine Bath is located at the south edge of Thessaloniki?s upper town, near and at the north of the Byzantine cistern in Olympiados St.

The Byzantine structure, having undergone multiple interventions over the centuries to accommodate the bathing customs of different periods, operated as a public bath until 1940.

Despite the interventions of more than seven hundred years, the 17x12.50m monument retains the typical, three-part arrangement of the Byzantine baths. From west to the east the following chambers are developed: (a) a vaulted, subsequently divided, antechamber, which served as a changing room, (b) two double halls heated by hypocaust ?the warm room (the tepidarium or chliaropsychrion) covered by barrel vaults and the hot room (the caldarium or thermolouterion), the south chamber of which was covered by a low dome that only on the outside is inscribed in an octagonal drum, while the north one by a monastic groin vault? and (c) a vaulted water reservoir, which seems to have been extended twice, at different times.

The furnace beneath the water reservoir was fed from the east side; besides heating the water it produced steam, which entered the caldarium through the above-floor vents opened on the wall in between, and hot air, which was channelled through the sub-floor passages to heat the floors.

Based on morphological and structural characteristics, the Byzantine monument can be dated to the first half of the 13th century; being a public, or possibly monastic, bathing establishment, the monument is the largest and best preserved of the few surviving Byzantine baths in Greece, and the sole survivor of the many baths in Thessaloniki mentioned in byzantine texts.

This rare of secular Byzantine architecture is an UNESCO World Cultural Heritage monument. It has been restored by the Ephorate of Antiquities of Thessaloniki City in the framework of the NSRF 2007-2013, and is now open to the public