A Nesting Doll of Churches.

This park on the outskirts of Rome boasts two ancient Roman aqueducts and a medieval tower.

A fairy tale castle in modern Rome.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

This bar and museum are devoted to the controversial comic book work of Kája Saudek.

A massive 1830s industrial site once known as Czechia's "Iron Heart" has been transformed into a playground of science, technology, and art.

Seven mini rowhouses fill the gap between 54 and 70 Westerstraat.

The world's first zoo for microbes collecting the horrible and wonderful things living on and around us.

A state-of-the-art medical facility from the Imperial era is now a derelict ruin.

Thirty creepy ghosts now inhabit this decaying 14th-century church.

What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

No need to strap in for a "ride" on this walkable roller coaster.

The Bauhaus-style former industrial complex is considered the world's most beautiful coal mine.

The monumental home of Prussia’s eccentric "Cannon King."

Tucked away in a small German apartment is an eclectic museum devoted to West African vodun culture.

Swarms of dainty flying insects swarm into the Petaloudes Valley to get busy.

Free candle-lit art gallery, accompanied by a live piano score.

Running since 1864, this clock has yet to be wound, one of the longest-running science experiments known.

One of the world's steepest streets seems to have houses sliding down it.

Known for the tunnel that leads visitors to the water.

One of New Zealand’s few castles boasts beautiful gardens, grand architecture, and a history filled with family drama.

During the rainy season, this temple is almost entirely submerged, accessible only by boat.

The deepest sinkhole in Central Europe comes with a grisly tale and an unusual nickname: “The Stepmother Abyss.”