The mosaic edifice was discovered during blocks of flats construction works on the south-west coast of the city, in 1959. The imposing edifice was built in ancient times on three terraces, cut in the sea-wall slope; they used to be leveled in order to ensure the building stability. The edifice was situated on the very quays of the old Tomitan harbor; from its level the first series of rooms opened. The edifice included eleven vaulted rooms used as warehouses for the goods brought by the trade ships coming to the port. The access to the next two terraces was ensured by some massive limestone stairs. The second level was similar to the first. It used to also have eleven vaulted rooms for the same purpose as the first ones. The discovery of a group of imported products stored in two vaulted rooms on the second terrace of the mosaic edifice provides a complete image upon the imports in the Roman-Byzantine period: an impressive quantity of stamped ceramics, rush-lamps, rush-lamps molds, amphorae full of different organic substances (turpentine, mastix, stirax, colofonium, incense, mirth), as well as amphorae carrying iron nails, piles of iron ingots, 8 iron anchors, marble plates.
The outline of the third level was totally different compared to the other two. Here, there used to be a huge sumptuous and undivided room. The room used to have a rich decoration, and the improvised platform on the north-eastern side shows that the room had a special and different purpose. Initially, this room communicated with the city through an entrance situated on the north-eastern side. Later on, the entrance was bricked up and it was used as a niche. There was another entrance to this part of the complex through the vestibulum at its western corner. The second terrace vaults collapsed almost entirely and damaged the rooms inside and mostly the mosaic the vaults used to support. The room surface was covered by a polychrome mosaic decorated with vegetal and geometric motifs; the mosaic covered an area of about 2,000 m2, of which about 400 m2 are still preserved.