Sofiyski metropoliten, also colloquially called Софийско метро, translit. Sofiyskо metro) is the rapid transit network servicing the Bulgarian capital city Sofia. It began operation on January 28, 1998.[1] As of July 2016[update], the Sofia Metro consists of two interconnected lines, serving 35 stations, with a total route length of 40.0 kilometres (24.9 mi)[1][5][3][4] being among the top 30 of the most extensive European metro systems.