These blingy, baubled skeletons lie in glass boxes inside a baroque Bavarian church.

A house of bones — but nobody is quite sure to whom they belong.

Mummified monks and the accidentally interred, in a 17th-century crypt.

This churchyard arbor is surrounded by hundreds of gravestones placed there by author Thomas Hardy.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

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

Europe's second largest ossuary wasn't discovered until 2001.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

An exquisite Baroque church in Vienna's old town.

The solemn exterior conceals an opulent interior of this 17th century church.

This cubist Vienna church building looks like some sort of alien stonehenge.

Op-art architecture designed for happiness.

This museum promotes informed contraception by documenting its often secret past.

Collection dedicated to funeral rites, equipment, and mourning rituals of the Viennese.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

Macabre museum devoted to historical Viennese murders.

Peek through a transparent pyramid and drink in the mountain made of books.

The beautiful baroque library of the Hapsburg empire.

A historic London pub with prison cells in the cellar and a "spy room" on the second floor.

Near Birmingham, England three and a half miles of top-secret tunnels housed a World War II “shadow factory” and a Cold War nuclear bunker.

One of New York's best collections of pinball is hidden in a secret bar in the back of this laundromat.

Hidden behind Lincoln's head is a 70-foot-long chamber containing enamel plates documenting American history, sealed in a teakwood box in a titanium vault.

A Cold War secret surveillance tower used to spy on radio communications.