Historical version 5 of Victoria Line (view current version)
The Victoria Line
Constructed in the 1960s, finished in the '70s; lovely light blue colour, and operating entirely underground. First tube line to have automatic operation. Not quite as shiny as it once was, but still damned fast and boasts a disproportionate number of connections.
Line guide: http://www.davros.org/rail/culg/victoria.html
Rolling stock: http://metadyne.tripod.com/1967tubeStock.html
History and timetables: http://www.thetube.com/content/faq/lines/Victoria.asp