The first piece of public art dedicated to LGBT rights.

A quiet and contemplative oasis in the middle of New York's bustle and riot.

Elevated freight railway turned wildly successful urban park.

The mysterious canine hides atop a drain pipe on the back of the building, some say as a sneaky shoutout to Yale.

Nassau Hall has served as army barracks, a museum, and played a key role in the American Revolution.

This elaborate towering structure was once famed for its revolutionary height.

Yo, Adrian!

When it comes to handsignals (and colonialism) rock always beats scissors.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

An overlooked memorial honoring the local Washington residents who died in World War I.

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

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

Look closely and you’ll notice that the color changes a third of the way up the tower.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

The walls of the iconic dome are hollow and have a secret stairway.

These unusual rooms on wheels are holdovers from the 1960s.

At 207 feet, one of the world's longest continuous escalators.

This isn't your average roadway—it's actually a National Park and a transportation pioneer.

In 1932, Americans honored their first president's 200th birthday by planting trees.

A monument to the one-armed geologist who led the first documented expeditions through the Grand Canyon.

This small interfaith chapel lies not far from the rim of the Grand Canyon.

Crafted in 1911, this steam locomotive spent its entire working life in Flagstaff.