This Czar-funded, onion-domed, lavishly muraled Orthodox Church played a starring role in "The Deer Hunter."

An architect transformed this abandoned cement factory into his castle-like workshop.

The "Greatest Sewer" of ancient Rome is one of the oldest sewer systems in the world, and is still in use.

High atop a Mexican rainforest mountain, this ancient pyramid once drew pilgrims countries away.

A mysterious monument where a woman who records say never existed was burnt alive for being a witch.

A huge musical instrument played by the ocean.

These expertly crafted, scientifically accurate glass sea creatures were once an international phenomenon.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

Hundreds of secret cabinets built into the walls of legendary poisoner's private work room.

The Florence Nightingale Museum is home to the famous nurse's most treasured possession: her beloved pet owl.

A historic house devoted to the teachings of a 1700's prophetess and her mysterious box of revelations.

Bonsai garden in Oakland is curated by the first non-Japanese female bonsai master in the United States.

A computer bug so primitive it was an actual insect.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Thirty architectural gems from the 19th- and early 20th-century Tokyo were restored and relocated to this space.

An institution dedicated to curiosity, logic, riddles, and Mongolia's long history of puzzles.

A 90-year-old underground water reservoir offers a more industrial kind of tranquility.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

The world's longest and deepest train tunnel.

The tallest outdoor elevator in Europe rockets passengers on a dizzyingly precarious ride to the top of a mountain.

A favorite with sightseers, this Norwegian funicular provides easy access to a stunning view of Bergen and its environs.

Traversing steep Alpine slopes, this engineering marvel is one of the longest and highest funiculars in the world.

Hamburgers are intensely proud of their tunnel beneath the river.