One of the world's tallest flagpoles.

A Medieval Water Tower in the Heart of Massachusetts.

Plaques on its facade commemorate the Tiber's most destructive deluges.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

The oldest continuously inhabited street in America.

Of all the unique artifacts inside this library, a mummified hand stands out among the others.

The longest step street in the city.

This Bronx apartment building is officially recognized as the birthplace of hip-hop.

Final resting place of Typhoid Mary.

This plot of old-growth forest is the largest surviving remnant of New York City's original woodland.

The engineering wonder and pleasure dome of a much-maligned emperor still holds undiscovered secrets.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

The Cycladic architecture makes this Athens neighborhood feel like an island paradise hidden in the shadow of the Acropolis.

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

This giant monument of the RCA mascot is a beloved fixture in Albany, New York.

This striking arch, one of the first architectural elements constructed in Prospect Park, was recently restored to its original glory.

Waterway populated with abandoned projects, including a submarine.

New York's oldest concrete structure is being preserved thanks to the gentrification of Whole Foods.

The one-stop shop for all of your superhero (or evil arch-nemesis) needs.

An eerie diorama that captures the majestic nature of a few prehistoric-looking beasts.

This unusual apartment building may be Brooklyn's own version of the Leaning Tower of Pisa.

The unassuming structure was part of a Major League Baseball stadium.

This outdoor gallery of sculptures along the East River was once a landfill.