One of the steepest streets in the United States makes an intriguing challenge for cyclists.

This statue of one of baseball’s greatest pitchers looks like something out of a sci-fi horror movie.

Submerged trees jut ghost-like out of an idyllic turquoise mountain lake.

The oldest building in the District of Columbia was preserved because of a mistaken connection to George Washington.

Architecture lovers won’t stop touching the National Gallery's 19.5 degree marble prow.

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

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

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.

After starting as a whimsical tourist attraction that eventually found its way to ruin, these renovated canals offer a lush and exotic locale on the Pacific Coast.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A building so large that it has its own weather.

The little-known, 300-year history of the area includes former lives as a bustling tobacco port, parking lot, and industrial dump.

I-95's Tijuana-style celebration of kitsch at the Carolina border.

Equal parts record-breaking temple to consumerism and bizarre fun park, it's more than you think it is...

The most confusing clock in New York.

An historic and oft-filmed spot for musclebound iron pumpers on the Pacific coast.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

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

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

The whole world in one water tank.

WWII-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers. .

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

Funded by John D. Rockefeller, this is one of the earliest, and most beautiful, shopping arcades in America.

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