Built following the War of 1812, this fort has withstood hurricanes for centuries.

The second-largest ceremonial mound in the United States is an artificial hill that is loosely shaped like a pentagon.

An eerie and beautiful group of columns mark the site of a grand mansion lost to time and fire.

Once one of the largest producers of pig iron in the world.

Pilgrimage site for star-crossed lovers.

The once forbidden "secret cabinet" of erotic art from excavations of Pompeii and Herculaneum.

Erotic art covers the walls of the largest ancient pleasure palace.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

Two stone columns flank the grand Venice square, but there were supposed to be three.

An extensive collection of reliquaries containing the bones of saints housed in the largest Catholic church in Venice.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

Go inside to really appreciate this 500-year-old technological masterpiece.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

A Nesting Doll of Churches.

The final resting place of the poets Shelley and Keats.

2300-year-old Roman road connecting the empire.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

Alabama has a fiberglass Stonehenge. With apologies to Spinal Tap, this one is full-size.

This replica of the Greek structure is in the heart of Nashville.

At 135 years old and counting, this historic print shop is heaven for poster nerds and music buffs.

One Confederate statue that accurately reflects the ugliness of its subject.

Civil War soldiers, captains of industry, and paupers all interred on historic grounds.

Beside some power panels, a plaque celebrates the history of an alternate world.