Largest display of Wesleyana anywhere in the world.

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

A derelict bit of infrastructure from the canal that once ran through D.C. is landlocked in the heart of the city.

The U.S. Fish Commission’s effort to mass produce carp.

The remains of Martha, the last known passenger pigeon, serve as a tool to educate about conservation.

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

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

A spectacular tribute to statesman and philanthropist Andrew Mellon.

The only Leonardo Da Vinci painting in the Western Hemisphere.

The trunks of 3,000 year-old trees lurk beneath the surface of this crystal clear lake in Oregon.

The slate extracted from these Pennsylvania quarries was once hailed as the finest in the world.

Canyon walls shrouded in ferns.

A suspended garden, now gone, once hung in the middle of this abandoned church.

This 19th century granite fortification is one of the most well preserved forts in New England.

If a visit to this farmhouse feels as if you are stepping into an artistic masterpiece, you’d be right.

This $3 million model train takes you through Chicago, Seattle, and the thousands of miles in between.

Built by prisoners of war, the largest small-scale model ever built includes eight miles of tiny streams that now sit abandoned.