A cave interior in the shape of the ancient rhinoceros, created by lava cooling around its carcass.

Site of the greatest known waterfall that ever existed.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

The former home of the reclusive "Weird Wendels" who dominated New York real estate a century before Donald Trump.

Locals dubbed it the "Owl Building" because of its bird-like appearance.

A "Texanic" (gigantic Texas) collection of Art Deco architecture at Dallas' historic Fair Park.

A 2,500-pound wooden nickel makes this woodworking museum easy to spot from the road.

The upstairs reading room is packed with millions of rare books, literary manuscripts, and historical treasures.

This Seattle museum displays the history of the telephone through an impressive collection of telecom equipment.

This scenic gorge is named after one of the most famous Bigfoot attacks in pseudohistory.

A tiny red pebble marks what may be the quietest outdoor spot in the United States.

The strange phenomenon causing gravity to "work backwards" on this hill has been blamed on the paranormal.

A fine, large-aperture telescope available for public use.

Cave carved out of a huge snow drift collapsed killing one and injuring five in July 2015.

This historic building provides a powerful glimpse into the lives of Japanese Americans forced to relocate during World War II.

Housing the National Women's Party since 1929, this historic house is now a monument to the fight for gender equality.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

A historic estate packed with George Washington's heirlooms, and its own nuclear bunker.

Waterway populated with abandoned projects, including a submarine.

The gilded vestiges of a sterling department store can still be found in a Brooklyn shopping center.

Surprisingly aquamarine waters fill deep lakes formed at the end of the last ice age.

This former Texas landfill is flush with 300 million-year-old fossils, all fit for the taking.

Decades of discarded bottle caps line this alleyway, a fixture of Texas A&M.

An enormous warehouse filled with parade floats collected from over 50 years of patriotic celebrations.