Once America’s most beautiful army base, this abandoned military fort on the coast of Monterey Bay has been left to the elements.

The first safe in this California town had to hold all the gold.

This remarkably simple jail went over a century without an escape.

This municipal playground was co-created by the father of one of the most playful characters ever.

This eagle-topped spire remembers the military commander who snatched up California for the United States.

The oldest U.S. Government building in California, and it's State Historic Landmark #1.

Two rocks in a perpetual kiss and one of "the most romantic spot in America."

Every year, over 25,000 monarchs overwinter in Pacific Grove.

The oldest lighthouse on America's west coast no longer needs keepers, yet they maintain the site anyhow.

This bridge was constructed from the rubble of the infamous Bastille.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

France's national museum of scientific and industrial instruments.

A horde of stray cats rule in this secluded Parisian cemetery under a bridge.

The celebrated eyesore created by starry-eyed sweethearts.

The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

This 14th century tower house was once the home of Irish poet W.B. Yeats.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

A hugely vast Irish landscape of barren rock that stretches for miles.

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

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

An ancient neolithic tomb that only sees the sun twice a year.

One of the most popular megalithic sites in Ireland stands as a humbler version of Stonehenge.