The ominously named cave is home to some remarkable ancient art.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

Tubing through a cave lit with glowworms is a magical underground experience.

Eat your Big Mac in a DC-3.

A museum devoted entirely to the rattlesnakes and snake-related art.

The ruins of a medieval monastery named after a type of tree.

A tribute to the incredible generosity the Choctaw Nation showed the Irish people during the Great Famine.

These gigantic skeletons tower over visitors and provide insight into the creatures that once ruled over Ireland.

This permanent collection of preserved bodies taken from Irish bogs is one of the leading authorities on such morbid mummies.

Dublin's "Dead Zoo" serves as a window to Victorian museum design.

Horse cemetery on the grounds of Blarney Castle.

A tribute to the intrepid explorer and his crew who perished in terrible conditions on an ill-fated expedition to the Arctic.

The world's largest collection of ship figureheads includes figures from legends and history alike, from Sir Lancelot to Abraham Lincoln.

The sculpture of the deceased cockatoo flops atop its personal plinth.

The arching stretch of London's longest street holds many reminders of the area's maritime past.

The London pub overlooks where the Mayflower was moored before setting sail for the New World.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

Giant, friendly pelicans in Central London, the most unlikely of places.

The beloved beast's taxidermy remains sit in the Natural History Museum's cafe.

Repository for more than 22 million pickled specimens.

Catacombs turned marketplace.

The popularity of Sherlock Holmes led to the creation of his fictional address, turning the orderly London street numbers askew.

These official units of measurement—including chains and perches—lie hidden beneath tourists' feet in a popular London hub.

Originally meant to hold a statue of King William IV, this support sat empty for years. Today, it hosts a rotating cast of public artwork.