Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

Colorful and chaotic stacked hotel in North Holland.

Terrifying derelict military hospital once housed a recuperating Hitler.

Berlin's old airport.

Cold war icon and onetime "hole" in the iron curtain.

An old department store turned Nazi prison turned artist commune.

Blitzkrieg bop your way through Berlin's Ramones Museum.

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

The celebrated eyesore created by starry-eyed sweethearts.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

A church of bones, decorated with 40,000 human skeletons.

Monument to a suicide protesting the Soviet invasion.

Macabre astrological automaton clock dating to the late 1400s.

Two stunning 17th-century libraries and a cabinet of curiosities.

Standing in a state of "arrested decay," this ghost town allows for a detailed peek into Gold Rush life in an unusually harsh climate.