The central room of the east wing is one of the most important rooms in the entire thermal spa. Its importance lies in the fact that it is where the thermal water that gave life to the whole complex came from in Roman times.

The water’s curative and therapeutic properties also gave it a sacred appearance which turned this room into a small sacred space, a kind of chapel. On the north wall, the remains of a small altar can still be seen, framed by two pilasters that must have housed several images of divinities of health, which probably included Apollo. This was also the only room in the entire thermal spa that had stucco walls decorated with polychrome mural paintings.