Budapest Metro in Hungary first became operational with the opening of Line 1 in May 1896. In 2002, the line was listed as a World Heritage Site by UNESCO.

The London Underground is famously the world's oldest subsurface metro system - and many would argue that it is by far the ...

Kiev's three lines cut across the city, serving its almost three million residents, and the system is home to what is claimed to be the world's deepest subway station, almost 350 feet below street ...