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

Next to the Leaning Tower of Pisa is a cemetery home to ancient sarcophagi and disturbing murals.

The only visible reminders of an elaborate engineering project that kept the tower from reaching the tipping point.

A plaque on the base of this statue holds a bewitching design.

An 18th century fountain and two columns are all that remains of Rome's forgotten river harbor.

The first statue to be added to Saint Peter's Square in over 350 years is an ode to migrants and refugees around the world.

These spartan apartments are provided to clergymen visiting Vatican City.

This vast masterpiece of Moroccan architecture spreads across 20 acres.

Remote, volcanic island that Darwin, Hooker, and the Royal Navy shaped into a thriving, artificial ecosystem.

Traditional 11th-century outdoor tannery.

An awe-inspiring mosque in Morocco with one of the tallest minarets in the world.

Single runway interrupted by a busy road that cuts across its middle.

There was a top secret plan during World War II to seal a group of soldiers inside the rock.

Engineering ingenuity during the battle of Gibraltar.

Red, white, and blue painted steps along with a Union Jack celebrate the outcome of Gibraltar's 1967 referendum.

Many of the tombs contain victims of yellow fever epidemics.

Overlooking a Scottish loch, this beautifully crumbling castle once inspired a poem by William Wordsworth.

Looking strangely like Rome's Colosseum, this unfinished tower has dominated the skyline for over 100 years.

This astonishingly geometric cave has inspired everyone from Jules Verne to Pink Floyd.

On a corner of the Ardmeanach peninsula on the Isle of Mull, a 50 million-year-old fossil tree hides in the coastal cliffs.

A small island abbey is the final resting place of many medieval Scottish monarchs, including the real Macbeth.

This educational and eco-friendly community is Iceland's "home of the sun."

This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

Inside this Icelandic greenhouse, geothermal energy keeps tomatoes warm and growing.