In the capital of Bulgaria, ruins of an old fortress and city wall have been discovered during the planning stage for the proposed lines 1 and 2. Two scenarios have been considered when planning the intersection beween those lines at Serdika station. The first option was to build the metro tunnels away from the archaeological site and to keep the archaeological research for later; the second option was to build the intersection beneath the archeological reserve, utilize the construction for excavation and set up a pedestrian underpass with an archaeological exposition. In cooperation with the Committee for Culture the second option has been chosen. [11, 15].
Exhibits in stations:
Serdika station (under construction): Thracian and Roman ruins of an old fortress will be integrated in the station.
"[Ding-dong] Vnimanie, vratite se zatvariat! Sledvashta stantsia: [station name]", meaning "Warning, the doors are closing! Next station [station name]". On arrival: "[Dong-ding-dong] Stantsia: [station name]".