A magical sinkhole on the Yucatán Peninsula is adorned with mini waterfalls and hanging vines.

No telescopes, no power, no gift shop: The Observatory of Chichen Itza, one of the world's oldest observatories, takes astronomy back to basics.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

This valley of hot springs and boiling mud pots is home to the record-holding "Geysir," which originated the English word.

The most powerful waterfall in all of Europe.

This elegant arc of a waterfall marks a religious turning point.

Iceland's "Smoky Valley" is a beautiful river that is shrouded in a constant cover of steam clouds.

The unique waterfall in Iceland's south features a backdrop of geometric black lava columns.

Medicinal spa created from the mineral-rich runoff of a geothermal power plant

The signs of a long buried road can still be found hidden beneath a London sewer grate.

This city square dates back to the Scottish Enlightenment and was home to some of Scotland's brightest minds.

Protecting the dead from opportunistic body snatchers.

Overlooked by many, the two famous Scottish warriors guard the main gate of Edinburgh Castle.

A sweet symbol marks the place where torturous executions were once carried out.

Many of Edinburgh's more unsavory characters spent their final days behind this door while awaiting their executions.

A 18th century graveyard and its astonishing cortege of macabre iconography.

This 17th-century street hidden beneath Edinburgh was once a breeding ground for the black death.

These steps offer a breathtaking view of one of Europe's most besieged fortresses.

This derelict superstructure was a very important warning system for the Soviet military.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

The record holder for the world’s largest peach.

This sprawling museum holds one man's giant collection of real tanks.

The oldest farmer's market in America is so ancient it was approved by the King of England.

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