Once thought to be the oldest living tree in the world, Methuselah was germinated before the Egyptian pyramids were built.

The "World's Largest Underground Business Complex," a 55,000,000-square-foot city underneath Missouri.

These unique toilets feature transparent glass covered in PDLC film.

A mother’s sweet tradition lives on with this unique memorial.

This former luxury resort in Kaua'i is now an abandoned relic.

An Elvis superfan built Denmark's own version of Graceland.

A homage to the King at the hotel where he revived his career.

Hawai'i's oldest wooden house was shipped around Cape Horn from Boston in 1820.

A trading post in the North Pole where children send letters.

Massive mounds of golden sand look like a desert landscape randomly plopped in an Arctic forest.

This whimsical stacked cabin looks like something out of a children's book.

At night, this glittering musical tunnel draws skaters and photographers.

This lesser-known Frank Gehry building houses a treasure trove of cinema history.

This isolated island is often capped by its own fluffy cloud.

Located more than 600 feet beneath sea level, this tunnel boasts the world's first undersea roundabout.

Originally conceived as part of a proposed Arizona State Capitol building in the 1950s, this structure built in 2004 stands as a monument to the architect's legacy.

This picturesque cottage was the site of Ulysses S. Grant’s final and perhaps most important campaign.

The remains of the iconic train crash from the movie The Fugitive can still be found rusting along the Great Smoky Railroad.

This unassuming North Austin neighborhood was built to test the novel idea of home air conditioning.

The longest enclosed pedestrian bridge in the world spans 14 lanes of traffic and six rail tracks, all while lighting up the night sky.

A water pumping station disguised as a residential home to assuage concerned neighbors now tricks most passersby.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

One of the first intercontinental ballistic missile sites in the United States.

The Old Mill shown in the opening credits of “Gone With the Wind” is actually fairly new, and was never a mill at all.