This 50-foot-deep sinkhole created in the 14th century is home to rare plants and fungi.

At the foot of an active volcano sits a church miraculously spared by its lava.

An overgrown and largely forgotten cemetery lies hidden within the outskirts of Amsterdam.

The only surviving piece of Copenhagen's 16th-century defensive wall.

This colonial fort is an intriguing example of Renaissance military architecture.

This ancient statue of Dionysus lies unfinished and abandoned in one of Greece's oldest quarries.

On special occasions, one of the world's tallest artificial waterfalls gushes down the side of this Chinese skyscraper.

After years of slow decline, a derelict Gothic castle is now being restored to life.

This sprawling 18th-century cemetery features unique and beautiful gravestones, including one shaped like a tree.

These spectacular, symbolic serpents lie within the shadow of the Great Temple.

This forgotten Frank Lloyd Wright house is an architectural marvel at the end of a sleepy residential street.

This collector's home is a constant work in progress.

Assemble a masterpiece at the first and only North American school exclusively dedicated to mosaic art.

A lavender labyrinth so large it’s visible on Google Earth.

This rickety old shed hides a trove of secondhand literary treasures.

This steel frame is a skeletal mirage of a lost 16th-century stone building.

Myanmar's beautiful cemetery for Allied soldiers who perished during World War II.

All that remains of a Japanese fishing vessel that ran aground in 1982.

These excavated burials from the Tarim Basin are wrapped in mystery.

Potato-peeling mannequins, Inca art, and a dangling tuber mobile help trace the history of fries at this Belgian museum.

Enjoy a slice while browsing the world's largest collection of pizza memorabilia.

Only 68 people per day are allowed to visit this New Zealand bird-watcher’s paradise.

This macabre masterpiece of a mural is one of Francisco Goya's "Black Paintings."

The family compound and final resting place for the philosopher, Confucius, and over 100,000 of his descendants.