On Waikīkī Beach, a monument to four extraordinary individuals of dual male and female spirits who brought the healing arts from Tahiti to Hawai'i.

France's most famous cemetery, with some of its most curious tombs.

One of the oldest medical collections in Europe focusing on rare surgical instruments.

The underground sanctuary of a mysterious ancient cult.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

This ancient Roman prison is decorated with an upside-down cross not as blasphemy but as saintly tribute.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

One of several skulls claiming to belong to the beheaded St. John the Baptist is on display at this Roman church.

A forgotten "city of water" underneath the famous Trevi district.

This London pub hides a peculiar secret: a recreation of the rooms shared at 221b Baker Street by Sherlock Holmes and Dr. Watson.

A tiny house showcases the busy life of a local gnome.

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

This riverside restaurant has been serving customers since 1146.

From Ancient Rome to WWII, Neupfarrplatz has over 2,000 years of history underneath its main square.

This "second" cemetery represents New Orleans' attempt to keep cholera at bay.

The oldest cemetery in New Orleans, resting peacefully for over 200 years now.

This set of rickety spaceships are prepared to give alien travelers a place to relax and go to the bathroom.

Once luxurious, these oceanfront beach homes have been left to succumb to the elements as the beach is slowly washed away.

This bare tree might not have leaves but it is constantly clothed in festive decorations left by mysterious local benefactors.

Settled in 1696, abandoned after the Revolutionary War.

The only working large-scale tea plantation in the United States.

This recently rediscovered Civil War-era submarine was the first to ever sink an enemy ship.

Dedicated to the history of the health sciences.

Dental instruments from the illustrious history of American dentistry.