An 18th-century Spanish watchtower made entirely of seashell and concrete.

A tribute to Ponce de Leon's supposed quest for eternal youth.

The ruins of this antebellum sugar plantation are the end result of a Seminole attack during the Florida Wars of 1836.

A luxurious 1880s hotel with its fair share of Tiffany stained glass, Edison electricity, and of course, ghosts.

If it feels like a speakeasy, that’s because it probably was one.

Once forgotten, this strip of sand was a rare beachside haven for Black Americans in Atlantic City.

The rusting remains are visible sticking out of the waters of the Delaware Bay.

World War II bunker still standing on the New Jersey beach.

Step inside Lucy, the world's largest "elephant."

Pompeii's less famous neighbor is still revealing her secrets.

This shining multicolored metro station deep under Naples is said to be the most beautiful in Europe.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

Baroque celebration of the end of the Great Plague of Vienna.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

The beautiful baroque library of the Hapsburg empire.

Through the decades, Black music stars have performed at this historic hub for music and the arts.

The first memorial dedicated solely to the Black troops who fought for the Union.

A gorgeous mural outside a beloved D.C. restaurant pays homage to famous Black Americans.

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

Corn-inthian columns with a uniquely American take on neoclassical architecture.

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

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

Was there a small "backpack nuke" hidden in the attic? JFK apparently thought so.

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