America's greatest forgotten garden and the former stomping grounds of Son of Sam.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

The largest of London's subterranean rivers and once a mad, bad center of London life.

Theme park featuring miniature replicas of European monuments.

The John Snow Memorial marks the epicenter of London's 1854 cholera epidemic.

An architectural oddity of six stories, accessed by graceful ramps.

One of the world's most complex timepieces.

The bizarre visions of H.R. Giger, tucked away in a Swiss medieval city.

A nearly 500-year-old sculpture depicts a man eating a sack of babies, and no one is sure why.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

The hidden "ballroom" under a mansion lake was built by a criminal who ate a cyanide pill during his trial.

A museum in the childhood house of a medical pioneer.

Electrical curiosity museum housed in an old transformer station.

Once the home of a hermetic monk, this cave now houses a small church.

Hungarian self-built castle.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

Handsomely crafted representations of our round planet.

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

Macabre astrological automaton clock dating to the late 1400s.

"World's largest scrap metal sculpture" stands in an outdoor sculpture garden in the middle of Wisconsin.

19th century tunnels burrowed under Liverpool.

Former self-sufficient mental institution now a planned community.

A massive forgotten storehouse from 1913 on the Brooklyn Waterfront has a spectacular view of Brooklyn.