A remarkably intact castle that once was the largest in Ireland.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

The oldest pub in Ireland may also be the oldest surviving bar in the entire world.

A moody and picturesque riverside ruin overgrown with vegetation.

An Iron Age fort on the edge of a seaside cliff offers a glimpse into an ancient, mystical world.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

The 700-year-old fortress was the site of Count Orlok's castle in "Nosferatu."

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Mosaics, storks, and brothels—this ancient city has it all.

Huge stone depressions which may have acted as an Incan agricultural experiment.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

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

The only home that Alexander Hamilton ever owned has a history almost as troubled as his own.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

A New York garbage depot holds a secret collection of weird and wonderful refuse.

One of the only single-person private gravesites in New York City.

Behind a bodega is a small museum of relics and ephemera showcasing the history of New York.

A modern zoetrope on the New York City subway.

New York City's smallest piece of private property.

Tucked in the back of this amazing antique store is an important piece of medical history.

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

A hands-on traveling collection of the innovative devices of yesteryear.

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

A terrific purveyor of natural history objects and curios.