The Glasgow Subway is an underground rapid transit system in Glasgow, Scotland. Opened on 14 December 1896, it is the third-oldest underground metro system in the world after the London Underground, and the Budapest Metro. It is also one of the very few railways in the world with a track running gauge of 4 ft (1,219 mm). Originally a cable railway, the subway was later electrified, but the double-track circular line was never expanded. The line was originally known as the Glasgow District Subway, but was later renamed Glasgow Subway Railway. It was so called when taken over by the Glasgow Corporation who renamed it the Glasgow Underground in 1936. Despite this rebranding, many Glaswegians continued to refer to the network as "the Subway". In 2003 the name "Subway" was officially readopted