A 140-year-old castle with underground caves hidden in San Francisco.

The center of the only hemisphere that awards visitors with a commemorative coin.

These murals stand as reminders to the troubled history of this Northern Ireland city.

The ruins of a once-grand mansion in Northern Ireland are now thought to be haunted.

A peace symbol in Northern Ireland is among the world's largest hedge mazes.

The resting place of the man known as “The Father of Irish Tourism.”

This memorial site offers scenic views and a peaceful place for reflection.

This former World War II torpedo testing location is now an important nesting site for migratory birds.

This massive monument has been telling the time for 150 years—at a slight angle.

Legend says the water within these mysterious sacred springs stays cold even when boiled.

It was once nicknamed "the most bombed hotel in Europe."

It is said a heartbroken man visited the gap every day to stare blankly out at the sea.

A meandering boardwalk across the bogland leads to a "stairway to heaven" with sublime views.

The oldest remaining frame residence in Minneapolis.

A Perpetually Under construction Park.

A butcher shop in Minneapolis has all the meats and cheeses you’d expect from any of its kind—except that all the products are vegan.

A bronze statue on a downtown corner honors Minneapolis's favorite career gal.

The gorgeous library at Trinity College is home to remarkable treasures of Irish identity.

A house and yard adorned with bizarre concrete sculptures in a Milwaukee suburb.

This 18th-century fort surrounded by a moat was used to store gun powder and ammunition, and now sits in the middle of a large part in Dublin.

A guitar mounted on a wall in Temple Bar honors the Irish musician.

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

This supermarket offers shoppers a window into the past alongside their groceries.

This statue celebrating everyday life in Dublin has a few unsavory nicknames.