An intricately carved Viking church overlooks a glistening fjord.

This ancient cave is home to a museum, bar, and is filled with fluorescent minerals.

A rare opportunity to drive across the ocean floor.

Accessible only at low tide, the deserted island is dotted with World War II ruins.

This tiny island featuring 9th-century Viking ruins is only accessible at low tide.

A rocky sea serpent hides caves, blowholes, and a spectacular natural bridge.

A island reachable by a causeway at low tide is possibly one of the earliest Western European locations to be identified in text.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Sometimes an island, sometimes a rocky outcropping connected to the world by a tiny suspension bridge.

This bike path traverses the treetops.

A bike train runs along a disused railway line through the tranquil French countryside.

This bike path was sunk below water level for maximum wonder.

Cycle the solar system—from the sun to Pluto—right here on earth.

Inspired by "The Starry Night" this Dutch bike path turns into a glowing work of art each night.

The 43-mile route crosses through six islands with gorgeous views of the Seto Inland Sea.

Inside this 11th-century church, a medieval-style tomb of the World War I hero known as "Lawrence of Arabia."

You can crawl inside this atmospheric 5,000-year-old tomb.

This Mexico City subway station will make you feel like you've been transported to the London Underground.

A Mexico City subway station boasts a hidden museum, complete with a working radio booth.

Just your average Marie Antoinette–themed speakeasy in an abandoned 19th-century subway tunnel.

One of the last remaining Carpenter Gothic churches is situated on a wildflower conservatory overlooking the bay.

Taxidermied animals galore, by appointment only.

Time stands still at this serene burial ground in the center of Budapest.

The haunting cadaver tomb of a famous French poet, playwright, and filmmaker.