Kirovsko-Vyborgskaya Line (Russian: Кировско-Вы́боргская ли́ния, the line between the city's Kirovsky District and Vyborgsky District) is the oldest line of the Saint Petersburg Metro, opened in 1955. The original stations are very beautiful and elaborately decorated, especially Avtovo and Narvskaya. The line connects four out of five Saint Petersburg's main railway stations. In 1995, a flooding occurred in a tunnel between Lesnaya and Ploschad Muzhestva stations and, for nine years, the line was separated into two independent segments (the gap was connected by a shuttle bus route). The line is also the only one to feature shallow stations.
The line cuts Saint Petersburg centre on a northeast-southwest axis. In the south its alignment follows the shore of the Gulf of Finland. In the north it extends outside the city limits into the Leningrad oblast (it is the only line to stretch beyond the city boundary). The Kirovsko-Vyborgskaya Line generally coloured red on Metro maps.
* Upon the 1977 extension, the temporary station Dachnoye (which had been the terminus since 1966) and its tracks were demolished.
The transfer on Tekhnologichesky Institut is a cross-platform one. Last transfer to the Frunzensko-Primorskaya Line has opened via Pushkinskaya in 2008.
Two depots serve the line, Avtovo (№ 1) and Severnoe (№ 4), although when the lines separated in 1995 the Severnoe served the northern section whilst the Avtovo, along with other depots took over the southern section. As there was a large surplus in the north, conventional railway was used to transfer many of the trains to other depots. Upon the reunification of the two sections, the Severnoe depot's park was restored and the line became the first to start using eight-carriage trains, of which currently 34 and 20 trains are assigned respectively to the metro. Most of them are E, Em, Ema, and Emx trains built in the 1960s and 1970s.