Exact replica of the ancient monument, but much, much lighter.

A former mental hospital founded in the 1930s by a eugenicist who advocated for the forced sterilization of patients.

Also known as the Founding Church of Scientology.

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

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

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

This seemingly out-of-place gas station by the Watergate hotel was once described as the most expensive gas station in the world.

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

Art deco landmark on the outskirts of Washington, D.C.

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

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

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

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

Perhaps the most scandalous statue of America's first president.

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

A traveling postal dog covered 48 states and more than 140,000 miles, and he lives on as taxidermy, patched up with a rabbit's foot and a pig's ear.

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

A celebrity from the late Cretaceous period.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

An atomic bomb-proof strongbox protects the U.S. Constitution from terrorists and thieves.

The oldest continuously operating fish market in the United States.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.