Enjoy a slice while browsing the world's largest collection of pizza memorabilia.

In what is rumored to be an intentional act of spite, this memorial almost completely obscures the nearby grave of a senior officer.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

This waterfront museum in Maine is dedicated to the history of the smoked-herring trade.

The glowing blue Nymphaeum of Emperor Tiberius.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

A secretive collection featuring objects that were designed specifically for U.S. intelligence operations.

The world's oldest continuously operating airport was founded by the Wright Brothers.

A wondrous old library overlooking the nation's capital.

This grand gothic brewery has been pumping out suds for over a hundred years.

The oldest house in Manhattan is now a museum that remembers the home's sordid history of scandals, vice-presidents, and ghosts.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

The first "Hall of Fame" in America was designed by legendary Gilded Age architect Stanford White for what was then the NYU uptown campus.

Once America's longest-manned military fort, now an abandoned hulk.

The rough and tumble president's childhood home displays the shirt he was once shot in and the speech that saved him.

Ride the subways of yesteryear.

Lie in a hammock where George Washington stood.

In its day this historic fort held 100 cannons pointed in almost every direction to protect New York.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

This little museum is built on a theater that was once a wildly elaborate speakeasy.

Touching mementoes from those who didn't make it back from World War I still hang in one of New York's oldest bars.

A prohibition era watering hole for the police.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

Hear the tales of New York's most notorious criminals.