This eye-popping Icelandic crater lake is surrounded by red volcanic rock.

Haunting and beautiful trees, doomed to die.

This historic national park is covered in the stunning ruins of red rock pueblos.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

See massive fossils that are over 200 million years old in northeastern Arizona.

She stares out across six lanes of traffic, clutching a musket and infant with determination.

Remnants of a storybook amusement park hidden behind a strip mall.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

The tallest The Church of Jesus Christ of Latter-day Saints temple in the world soars above the Beltway.

A local farm's collection of unusual structures from a now defunct storybook amusement park.

An 18th-century Catholic church converted into an eccentric temple of music and bacchanalia.

A tradition unlike any other, this marks the site of the annual Groundhog's Day tradition.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

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.

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

The unique traffic pattern named for an influential urban planner is also known as the Pedestrian Scramble.

Washington's iconic carousel has a nice piece of Civil Rights history.

There’s a special club house at the top for the bell ringers.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

Decades before the scandal, this staircase on the river was a literal "water gate."

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

Fittingly, America's museum of architecture is itself a magnificently designed old building.