The House of the Mithraeum of Menander was built in the Hadrianic period (opus mixtum). It is situated to the west of an alley in which the Mithraeum of Lucretius Menander (room 14, described on a separate page) was installed. The building was excavated for the most part in the years 1931-1934.

The west part, along Via dei Balconi, consists of shops (1-3 and 5-7) on either side of an entrance hall (4) with an external staircase. The entrance hall leads to a vestibule (10) with high windows and doorways in the lateral walls. Apparently this vestibule did not have a roof, and provided light to large halls to the north and south (9 and 11). In the east wall of the halls are more windows and doorways (originally also windows). The halls presumably had a commercial function.

Many modifications can be seen, also in the alley behind the building (13). There are at least two later phases, one with opus vittatum. Small rooms were created in rooms 4, 9, 10 and 11, and in the alley. One of these, in hall room 10, has a curved back wall (10a). On the floor in front of the curved wall is a mosaic of two dolphins flanking a kantharos. In the north-east corner of hall 11 a basin was set.

The quality of the wall paintings and black-and-white mosaics suggest that at first the back part was changed to a habitation. Later the mithraeum was installed. On the north wall of room 12 a fragment of a wall painting was seen on the north wall, on a white background. Depicted were a red candelabrum of vegetation with green leaves and other red and yellow motifs. Room 11a has extensive remains of paintings, on the south and west wall, and on a brick pier in the north wall, but those on the south wall have been taken to the storage rooms. They have a white background. The socle has long rectangular red and yellow panels, and green leaves. Above the socle is one zone, with very high rectangles framed by red bands with narrow internal bands, yellow and red. Below the ceiling is a blue band with a stucco cornice. In the centre are little paintings: ducks and baskets with flowers and fruit, a temple and birds, birds and an apple. In room 11b and on the east wall of room 11 remains were seen of aediculae, red garlands with green leaves, a candelabrum of vegetation, and a small painting (red, yellow, green). Most scholars place the paintings in the reign of Marcus Aurelius, circa 160 - 170 AD.

In the south-east part is a very large oven of large tufa blocks (room 12). It has the size and appearance of ovens known from bakeries, but the date and purpose are not obvious. It could be that after the destruction by a fire of the nearby House of the Millstones, at the end of the third century, the loss of milling and kneading capacity could be compensated for by other bakeries, but not the loss of the oven, and that this one was built as a replacement. In the east wall of the room with the oven is a blocked doorway, in the west wall a large hole has been hacked out.