Work on the B line started in 1970 and construction began in 1977. The track was much harder to build, because the B line goes very deep, especially in places near the River Vltava, and it was necessary to excavate two transfer stations in difficult geological conditions. The Prague metro’s third line, named I. B, opened to the public on 2 November 1985. Reciprocal stations were built due to Czechoslovak-Soviet “friendship.” When Prazhskaja (Prague) station was opened in Moscow, Moskevská (Moscow, now renamed Anděl) station was opened in Prague.