Amazing and mysterious Neolithic settlement on Scotland's Orkney Islands.

Northern Ireland's Brobdingnagian stepping stones.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

This quaint mortuary chapel hides a stunning Celtic Revival and Art Nouveau interior.

This unassuming Victorian cemetery is the final resting place of author Lewis Carroll.

It's believed King John of England stayed at this 13th-century castle before riding off to sign the Magna Carta.

Visit the WWII bunker where the British won the battle for the skies.

In an isolated field near a dilapidated barn stands this chilling portrayal of the plight of the Nuba peoples of Sudan.

Human-made caves excavated to hide a secret society of wealthy pagans.

The world's first purpose-built motor racetrack was destroyed by the outbreak of two world wars.

The world's oldest model village.

This natural history collection contains the bones of a circus elephant that seem to be chasing a whale skeleton.

The sinister ruins of one of the worst dam failures of the 20th century lie in this astonishing alpine setting.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.

Commonly acknowledged as the only public monument to the Devil himself.

Over two centuries old and counting, Madrid's massive botanical garden contains one of Europe's only desert environments.

A lush indoor jungle fills this bustling Madrid transportation hub.

This amazing abuela became a diehard metal fan late in life and an icon of Madrid's '80s rock scene.

Tiny effigies of the victims of Edinburgh's famous Anatomy Murders.

The natural history museum displaying the British bird collections and dioramas of Edward Booth, free of charge.

This logic-defying 16th-century Tudor manor still stands to the delight and astonishment of onlookers.

This bridge is the first to be made entirely from iron, but designed like it was still made of wood.

On a site with a long military history, a 1980s shelter.