A cave 150 feet beneath Kansas City is the perfect climate for growing 10,000 delicate orchids.

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

On the outskirts of a desert trading village high on the Andean plain, steel giants have been destroyed by salt winds.

America's first federal monument.

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

A small triangle of DC grass is the final resting place of one of Sonny and Cher's songs.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

Once home to seven different roller coasters, Glen Echo has undergone many transformations since its founding in 1891.

Indents in the pavement are all that remain from a grisly death machine in Paris.