Ancient walls dating back to the 2nd-4th century were found during the reconstruction of Sofia's landmark Lavov Most (Lion's Bridge) on Thursday.

Excavations were scheduled in the area to coincide with the repair works after one of them was found while the second line of the Sofia Metro was being built a few years ago.

Combined with the two fresh discoveries, however, it gives experts ground to believe they have come across Roman walls that were part of an engineering facility that was connected to placing a bridge over the Perlovska river, Aleksandar Stanev, who leads the excavations, told Darik Radio.

Four more pieces could be registered soon, as there are indications other remains of walls are lying under the ground just off the river banks and "some of them even in river itself," Stanev added.