Millennium Underground Railway Museum

Budapest's M1 metro line opened on 2 May 1896, built in a remarkably fast 20 months specifically to serve the newly completed Andrássy Avenue in time for Hungary's millennium celebrations that same year. It was the first electrified underground railway on continental Europe (London's deeper Underground predates it by decades, but as a shallow, cut-and-cover electric line, the M1 claims the continental first), and it still operates today largely along its original 1896 route — a genuinely rare case of a 19th-century transit system remaining in daily public use rather than becoming a museum piece in its own right.

The Underground Railway Museum occupies an unusual, atmospheric space: when line M2 was built in the 1950s, engineers rerouted a section of the older M1 tunnel beneath Deák Ferenc tér to ease a sharp curve, leaving roughly 80 metres of the original 1896 tunnel sealed off and unused. Rather than filling it in, the transit authority converted it into a small exhibition space, opened to the public in 1975.