"The Stockholm Metro, or Stockholms tunnelbana, is the metro system in Stockholm, Sweden. The system has three main lines and one hundred stations, 47 of which are subterranean and 53 are aboveground (surface and elevated) stations."
"Stockholm's metro is well known for its decoration of the stations; it has been called the longest art exhibit in the world. Several of the stations (especially on the Blue line) are left with the bedrock exposed, crude and unfinished, or as part of the decorations."
Tremendous, indeed. I have never, in my years of mass transit, seen anything approximating this. Say what you will about the scale of D.C.'s tunnels and the baroque chandeliers of Moscow. I'll take the caves of Stockholm, thank you very much. Why on earth have the Swedes not let everyone know about this? Those cheeky Swedes.
(Thanks to things magazine for the heads up)