La discovery of the building and the analysis of old and new archaeological finds have clarified how the place became, already from the 1st century AD, and remained so at least until the 4th century AD, a residential district with public buildings. Incorporated into the city walls following the expansion of 440 AD, the complex in fact maintained its thermal function until the late antique age, when a significant renovation was undertaken.
The archaeological area includes a series of thermal rooms and still represents the most complete example of thermae documented in Neapolis. The plant, which covers an area of over 900 sq m, can be chronologically placed between the middle and the end of the 1st century AD. The building presumably had its main entrance on the ancient road axis (decumanus), traced by the current via Benedetto Croce, and was articulated in two parallel sectors: that of the pool, probably facing a courtyard with the function of a gymnasium, and that of the actual thermal rooms.
Of the ancient gymnasium, today only some traces of the perimeter wall of the porticoed area and a corridor that divided the gymnasium itself from the pool are visible; of the latter, initially covered, remains of the bench and access stairs are preserved instead. On the southern side of the excavation, an octagonal tank, of later age, was installed in an environment that probably originally constituted the entrance to the pool.
Along the entire western side there is also a water conduit, perhaps part of a larger pipeline derived from the Serino aqueduct.
The actual thermal rooms are arranged on two levels, one of which is underground. In the central ground floor room, the laconicum (for hot and dry air baths), connected to the tepidaria (for moderately warm baths), there are evident traces of channels: the tubuli, for the passage of hot air, and some hollow columns (suspensurae), which supported the floor suspended over the hypocaust.
In the northern area of the excavation there is a room, later transformed into a cistern, which, due to its northward orientation, would suggest a frigidarium (for cold water baths) or a nymphaeum.
Behind its southern wall there is finally a vestibule, from which the underground level was accessed. Some finds recovered during the exploration of the thermal building are exhibited in one of the rooms of the Museo dell’Opera di Santa Chiara, along with remains of sculptural furnishings and objects of common use and sacred art recovered from the Angevin age church (14th century), its cloister, and its monastery, which survived the fire that destroyed the monumental complex in 1943.
Opened in 1995 in some rooms of the monastery originally occupied by the nuns’ apartments, the Museum tells the construction stories and the historical-artistic development of the Franciscan citadel.
