These semi-natural waterfalls hint at the park's Victorian-era industrial past.

These mysterious religious carvings were once thought to be thousands of years old but are actually the work of modern eccentric.

The mystery of this small, brick pond eluded its possibly only investigator until his death.

Monty Python fans will recognize this abandoned mine as the Cave of the Killer Rabbit of Caerbannog.

Built to hold the worst of the worst of the Nazi war prisoners.

This enchanting hill is home to fairy lore and a sinister local mystery.

This castle was established by the 4th Duke of Montrose and is connected to the Buchanan Clan.

This former Baroque palace on the historic Calle Montcada is a rare architectural gem and was once the meeting place of an aristocratic scholarly society.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

These ancient sea caves hold Britain's highest concentration of Pictish rock carvings.

A trio of giant megalithic stones in the middle of a golf course.

Some cheeky plantings brighten an old slipway on Scotland's Firth of Forth.

The ruins of Scottish sea salt production.

This tiny little cave was said to have been a refuge for a saint with a glowing arm.

Bronze plates placed around this Scottish fishing village form a true-scale model of the solar system.

Stay in the one time home to one of Scotland's most notorious gentleman's sex clubs.

Soviet intelligence had a keen interest in the Cold War linguistic school at this old Scottish airfield.

A site of pagan worship which still attracts people looking for fairies.

This bronze statue was erected to honor a small Scottish town's beloved stray cat.

Every St. Andrews student knows to avoid this inscription for fear of a martyr's curse.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.

A palatial former bank building now houses what may be the poshest art venue (and former Tesco) in Belfast.