St Mary's Close, Edinburgh, Scotland is a maze of underground 17th streets, once home to hundreds of people, conditions were horrendous and once bubonic plague took hold and most of the people died it was sealed up and forgotten about until the 18th century when workman woking above punched through to the streets. It is now opened to the public and you can have a guided tour of this creepy place
Frankfurt's Bockenheimer Warte station. A weird subway entrance, looking like a train bursting through the sidewalk from below, is located in Frankfurt. Architect Zbiginiew Peter Pininski reported he felt inspired by surrealist artist René Magritte when creating it.