The construction of the subway in the Bulgarian capital began in the 1990s. As Sofia is one of the oldest cities in Europe, excavations have suffered several times as a result of some archeological finds and geological conformations of the territory. One of the stations where you can admire remains of Roman ruins and Thrace is that of Serdika. Since 2000 it has become a point of connection between line 1 and 2. To heat the rooms, Metro Diameter has installed 840 meters of Duck Strip thermostats, which, thanks to their flexibility, allow them to be inserted even in environments that present Architectural complexity. The thermal yields of our thermostrives are certified at the most important European laboratory in the field, that of the University of Stuttgart, according to the European standard EN 14037.