An exciting characteristic of the gallery space is the connection with the Late Roman period, thanks to the remains of an urban mansion, and its beautiful mosaics. In ancient times this place was within the Classical city walls. A rescue excavation on the lot on Lebessi and Porinou streets brought to light building remains dating from the Late Geometric Period (770-700 BC) to Late antiquity (4th /5th century AD). The polychrome mosaic floor, which is part of the 4th century villa (villa urbana) and features geometric and floral motifs, is preserved till now. Other parts of what was probably the same residence were discovered in 1968-1969 at 19-27 Makrygianni Street.

Some scholars believe that during Roman times the region south of the Acropolis was a residential area for members of the upper class, representatives of the Athenian political and intellectual elite. Although this area remained outside the fortification walls following the destructive invasion of Athens in 267 AD by the Herulians (an ancient Germanic tribe), during 4^th century AD (an era of recovery for the city), luxurious urban residences with private baths and household sanctuaries continued to be built here. Some buildings may have housed private schools.