More sculpture than building, this architecturally significant temple was built on the spot of Saint Peter's crucifixion.

Every inch of this chapel is covered in craftsmanship from across the world.

A marvel of Byzantine engineering under the streets of Istanbul.

Hungarian self-built castle.

Macabre astrological automaton clock dating to the late 1400s.

18th century opera in its original splendor.

It houses the remains of a 17th-century version of the Titanic.

Sweden's "good old days" painstakingly re-created in a model village.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

An old department store turned Nazi prison turned artist commune.

A whimsical and twisted animatronic monster tour beneath the streets of Berlin.

The most visited, and possibly most controversial, museum in Germany.