A fortified medieval basilica on the Caelian Hill preserves extraordinary frescoes and one of Rome's most beautiful hidden cloisters.

A museum dedicated to traditional Armenian clothing and their designer.

This graffitied 19th-century building was a prototype of European industrial architecture.

This serene, turquoise lake in an extraordinary nature reserve showcases a rare natural phenomenon.

The rocks are a time capsule of a 407-million-year-old Earth.

This structure was moved nearly 40 feet while people continued working inside it.

A beloved upside-down beacon off the coast of Northern Ireland.

From the dishes to the art, this Michelin-starred restaurant orbits around one beloved French melon.

For part of the year, this innovative greenhouse is painted white to keep the plants from getting scorched.

This structure atop a craggy cliff in one of the most beautiful parks in Paris boasts an unbeatable view.

An eerie, abandoned military base engulfed by nature and graffiti is now home to a local park.

The decaying ruins of a failed mining company’s water diversion project cling to the side of a desert canyon.

A statue of Vladimir Illyich Lenin guards this abandoned building in the "Forbidden City."

American artist J. Alden Weir purchased this 60-acre estate for $10 and a painting.

This mural honoring a drowned village has become a symbol of Welsh pride and patriotism.

An Ancestral Puebloan ruin that appears to burst into flames in the sunlight.

This Roman relic was discovered in Scotland by a mudlarking ferryman.

A medieval cave used to shelter local hermits now holds nearly 200 old Quaker gravestones.

A museum in the building where Nazi Germany signed its surrender tells the story of World War II from the Soviet perspective.

A humble ancient well where Scottish knight, Sir William Wallace, took his final drink.

This popular cave pool is truly magical, despite the crowds.

A 100-plus-year-old mill transformed into a hotel and restaurant.

Cascading outward, this waterfall creates the appearance of a flowing veil.

This park straddling the United States-Canadian border has been a symbol of peace since 1932.