The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

One of the oldest standing structures in Montgomery County, Maryland.

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

This shale formation along the Appalachian Trail once inspired the third president of the United States.

Built in the 1850s, this church was of the first five churches constructed in Harper's Ferry.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

This bridge over D.C.'s Rock Creek Park is sometimes called the "Buffalo Bridge" because of its four buffalo sculptures, which were cast from a single piece of bronze.

A gift from Japan, 17th-century lantern stands among the cherry trees at D.C.'s Tidal Basin.

One of the last mosaic tile facades found in the city.

One of the three perfect vellum copies of this historic book known to exist is on display in a specially-designed case.

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 grand marble structure next to the White House is Andrew Carnegie's temple to Pan-American diplomacy.

Coins and medals straight from the mint await visitors to this shop in the nation's capital.

This groundbreaking 16th-century map is known as "America's birth certificate."

The National Park Service’s best-kept secret with views that rival any in D.C.

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

A hidden passageway now marks the site of an assassination attempt on Ronald Reagan that some say broke a 140-year-old curse.

A muscular Art Deco monument represents the struggle between regulators and unbridled markets.

This forgotten boat elevator was an engineering marvel in its heyday.

A building shaped like the Army Corps of Engineers logo, because why not?

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

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