This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.

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

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

A musical instrument played by the sea.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

Macabre astrological automaton clock dating to the late 1400s.

An underground city of salt.

The former Nazi concentration camp stands as a museum to remember this dark chapter in European history.

The Guardian of Tallinn.

Major tourist destination known for its bubbling mud-pools and hot thermal springs.

Dolphins, ancient clams and hundreds of waterfalls make this one of the world's top tourist destinations.

The platform atop this verdant volcano was built with the help of a royal elephant.

It houses the remains of a 17th-century version of the Titanic.

A naturally occurring tunnel in this Nordic mountain makes it look like it's been shot.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Walk 2,300 feet above the ground on the "Troll's Tongue."

The great polar explorer is remembered in this far northern town, where he embarked on his final expedition.

This functioning parish church is also the site of many concert performances due to its wonderful acoustics.

These massive mitts are made of 30 tons of devotional bronze.

A 131-year-old wunderkammer of Texas history.

A graveyard of bathyspheres and diving bells paints a weirdly accurate account of ocean exploration's rickety history.

A monument celebrating the idea of reaching inaccessible places.

The largest market in Guyana, designed and built by the Edge Moor Iron Company of Delaware.

An abandoned colonial French prison notorious for its hellish conditions.