Not only is this the oldest stop of the Stockholm metro system, it is also an art gallery at the same time. The platforms are decorated in an elaborate manner with paintings, carvings, sculptures, and mosaics - just look at the walls and keep on admiring! The world’s longest art exhibition starts here at the T-Centralen station and stretches over 70 miles around.
Wikipedia https://en.wikipedia.org/wiki/T-Centralen
Address Norrmalm, 111 20 Stockholm, Sweden
Coordinates 59°19'54.819" N 18°3'39.398" E