One of our readers just sent in pictures of what could possibly be the “coolest” subway ever, built inside of a cave, or so it seems. Continue reading for more pictures.

The Stockholm Tunnelbana has three lines encompassing 110km of track and 100 stations of which 64km and 55 stations are underground. Several of the deep underground stations are cut into solid rock which were left with cave-like ceilings. The builders carved fascinating artistic objects out of the rock