Underground monastery and fortress.

Taking the subway here means doing so over a bridge located in the middle of an estuary.

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

A fountain standing as a testament to a doomed alliance.

Legend says if you stick your thumb in the hole and it gets wet your wish will be granted.

The most metal church of all time was built in record time because of an international, pious pissing contest.

1513 Turkish world map, full of European state secrets and snarky commentary.

This gem is often wrongly overshadowed by the larger, newer Metropolis church in Athens.

Where commuters walk through remnants of an ancient Greek necropolis.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

An ancient octagonal weather station named for the eight Greek gods of wind.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

The hallucinogenic center of the ancient world.

Monasteries on rock pillars, once accessible only by frayed ropes.

Statue of Lenin, from Cold War era Czechoslovakia, now in a neighborhood of Seattle.

From a neon Rapunzel to a bike traffic meter to a street fair color scheme, the most opened drawbridge in the US is a veritable art gallery.

This former coal gasification plant found a curious second life as a popular public park.

A wall of chewing gum moonlights as collective art.