One man's ambition created this psychedelic log home.

Fortified medieval tower house with lovely roof garden.

Swedish skyscraper with a 90° twist.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Romania's triumphal arch looks out over Bucharest.

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."

A cave's rare beauty held a cavernous secret hidden underground.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Statue in Salem of the woman who starred as the witch Samantha in the sitcom "Bewitched."

The inspiration for H.P. Lovecraft's horror stories and Batman's Arkham Asylum is now a condominium complex.

An architect's childhood fantasy treehouse made real.

Devilish landscape, once cinema home to giant alien bugs, now derelict roadside attraction.

A beautiful geyser under environmental threat.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

When ecosystems collide in the arid Southwest.

One woman's UFO-themed campground, complete with self-built energy vortexes, UFO-themed weddings, and magic bushes.

The largest self-built castle in the U.S., six decades in the making.

3,000 market stands in five former Zeppelin hangars.

Frequent fliers welcome in this airplane hotel.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This 1000 year old relic-filled cave monastery and UNESCO World Heritage Site also hosts an amazing micro-miniature museum.

The deepest metro station in the world.

A huge wooden clock that is so beautiful its creator was forcibly blinded.