A hidden beach at the end of a tunnel of mangrove trees.

Stay in a room with a view... of the bottom of the ocean.

A mysterious castle built as a monument to lost love.

Wading through a small lagoon reveals a secret, wild stretch of pristine beach.

An abandoned vacation home spent a decade taking on legends. It's now taking on water.

An underwater city for the dead.

The only swimming pool listed on the National Register of Historic Places is emptied and refilled each day with naturally filtered water.

The final resting place for the remains of 143 Habsburg royalty.

More gold than anywhere else, ever.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

A hip bar decorated with walls of golden skulls.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A semi-scholarly approach to sex.

Florida's oldest bar was once a morgue, complete with a hanging tree and gravestones.

12,000 sq. ft. museum tracing erotic art from antiquity to modern times.

Former villa and estate of James Deering developed to preserve native tropical forests.

The smallest museum in Basel, Switzerland, is a two-foot-by-two-foot window in the door of a 600-year-old house.

A bizarre house filled with an astounding array of collections.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

Huge masonic hall in Philadelphia with lavishly themed rooms.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

World's first "penitentiary," meant to be humane, drove men insane.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.