This Irish show cave is said to have been the site of a Viking massacre that claimed 1,000 lives.

Huge standing stones mark a site of megalithic mystery.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

This Fifth Avenue church has long been the favored worshiping place of Broadway actors and vaudeville performers.

The most confusing clock in New York.

The mummified relics of an American missionary.

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

Unrepaired walls from a 1920 anarchist bomb attack.

An artist's cute bronze subway sculptures belie his violent artistic past.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

A curious fountain that has no water and includes Satan, a crab, and 9 giraffes.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

Blighted Irish field and the ruins of a 19th-century cottage on the edge of urban Manhattan.

Mysterious 500-year-old tapestries depict a unicorn hunt.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

Elevated freight railway turned wildly successful urban park.

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

A terrific purveyor of natural history objects and curios.

England's oldest surviving hedge maze has been confusing visitors for over 300 years.

A beautiful opera house in the heart of Amazonia has recently restarted performances after a 90-year hiatus.

This striking, two-toned confluence of rivers is visible from space.