An architect's childhood fantasy treehouse made real.

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

One man's ambition created this psychedelic log home.

A beautiful geyser under environmental threat.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

This public square capitalized on a single Eagles reference to bring some life back to an Arizona town.

Walk through the actual strap iron cells and solitary chambers of Arizona Territory’s first prison.

A wild west cemetery in Tombstone, Arizona, provides a window into the Old West.

An old saloon in the West filled with history, and according to some, a few dozen ghosts.

Eons ago, a rushing lava river formed this pristine passage through solid rock.

See massive fossils that are over 200 million years old in northeastern Arizona.

This 4,000-foot-diameter hole is touted as "the most well known, best preserved meteorite crater on Earth."

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

The biblical sculpture honors those who lost their lives, homes and communities to the Chernobyl disaster.

The dining hall that nourishes workers in Chornobyl's Exclusion Zone is also open to visitors.

Abandoned ship reimagined as a street art canvas.

This strange moor has a song written about it, Bronze Age carvings, and an alien sighting.

The former Nazi Germany concentration camp stands as a museum to remember this dark chapter in European history.

An underground city of salt.

This one-time health resort was used by aristocrats around the world.

3,000 market stands in five former Zeppelin hangars.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

The medieval prince founded the first library in Ukraine at Saint Sophia's Cathedral where he was interred.

A tribute to a Ukrainian heroine who went undercover and killed several Nazi operatives.