Serpukhovsko-Timiryazevskaya line

The Serpukhovsko-Timiryazevskaya line (Russian: Серпухо́вско-Тимиря́зевская ли́ния, IPA:) (Line 9; Grey Line) sometimes colloquially referred to as Grey Line (Russian: серая линия), is a line of the Moscow Metro. Originally opened in 1983, it was extended throughout the 1980s and early 90s and again in the early 2000s. With its current length of 41.2 km (25.6 mi), it is among the longest lines of the Moscow Metro (all underground making it the world's 8th longest rapid transit tunnel). There are 25 stations on the line.