The Baths of the Baths-Superintendent Buticosus were built during the reign of Trajan (opus mixtum).
In the east part of the building, along Via degli Horrea Epagathiana, is a number of rooms behind a porticus. From here, through a vestibule, room 1 was reached. This was a waiting-room with benches. The west wall has a row of niches. In this room remains were found of garden-paintings, with green leaves and large yellow vessels. There is a similar painting in the tiny room 2, at the south end of 1. Room 3 leads to the heated rooms. On the floor is a Trajanic black-and-white mosaic of a naked male person, with the text:
Presumably this man was the baths-superintendent. In his hands are a bucket and a stick (perhaps a strigilis). In caldarium 4 are two basins. On the floor is another Trajanic black-and-white mosaic. In the centre are a Triton and a Nereid. They are surrounded by a sea-cow, dolphins, and hippocamps. The walls are decorated with white marble, preserved particularly well around the doorway. The walls of this room are very thick, suggesting that they carried a basin.
To the west of the caldarium is the Tempio Tetrastilo. To the west of the temple, in a room to the north of the pronaos of the Tempio di Ercole, was a waterwheel, with which ground water was led to the baths. The position of the wheel and the fact that a service corridor of the baths runs along the east side of the Tempio Tetrastilo suggest, that there was some tie between the baths and the religious complex of which the temple is a part (insula XV).
The north-west part of the building could also be reached through an alley starting from Via del Tempio di Ercole. The south part could originally be reached from Via della Foce, along the later building I,XIV,3.
Modifications took place in the middle of the second century: hypocausts were remade, doorways were blocked and covered with heating pipes.