Building IV,II,5 was set against the outer north-west wall of the Terme del Faro (IV,II,1). It was excavated in 1940. There are a few remains of Hadrianic opus mixtum. Most masonry belongs to the reign of Antoninus Pius or Marcus Aurelius (opus latericium; a coin of Marcus Aurelius was found). The only entrance was at the north end, from the paved square of the Caseggiato dell'Ercole (IV,II,3). At a later date an entrance was hacked out in the south-west wall. The north end of the building was modified extensively however: an elaborate stairwell was added, and a huge basin serving the baths (10).

The rooms of the building are on either side of a corridor (5). The ground floor may have been an apartment. There are two small, relatively dark rooms on the south-east side (6, 7). These may have been bedrooms (cubicula). On the north-west side are four rooms, along a public passage connecting the paved square and an unpaved square in the south part of the block. The two southern rooms along the passage (1, 2) originally had wide entrances in the facade. Later these were narrowed, and then blocked. In the facade of the two northern rooms windows have been preserved. At the south end of the corridor is a courtyard (4). The north-east entrance of corridor 5 was later blocked by the large room 10. From that time onwards the building could only be reached through openings in the south-west part, or - because these rough openings may be later - from the first floor.

In rooms 6 and 7 many remains of paintings were found, in room 6 with depictions of griffins and swans, animals accompanying Apollo (perhaps with a reference to Dionysus). They belong to the later second century.

Also in room 6 a cippus with a dedication to Isis and the Genius of the Apartment was found, by Claudius Pompeius Rusticus Diocles, miles frumentarius from the third Gallic legion. The frumentarii were messengers and police-officers, even secret agents.