When it came to designing his own small office building, the eccentric architect wasn't afraid to show the world what he could do.

There's a labyrinth of medieval chambers hidden deep below a 15th-century pub.

Hidden in a grotto 26 feet below Nottingham's oldest hotel, this stylish subterranean drinking den is notoriously hard to find.

A labyrinthine underworld of tunnels and caverns hides beneath the city.

The oldest inn in England served brew to the crusaders.

The largest lake in the Faroe Islands seems to be held hundreds of feet above sea level thanks to an optical illusion.

The narrow passages will challenge even the bravest driver.

An eccentric garden of sculptures crafted in India decorate an Irish green space dedicated to Alan Turing.

This 5,300-year-old tomb with mysterious carvings crowns an Irish mountain.

Wallabies live naturally on this Irish island.

A mysterious Neolithic tomb is perched along the edge of a modern golf course.

Local legend says the remains of Father Christmas lie within the medieval grounds.

Huge standing stones mark a site of megalithic mystery.

This ancient Irish religious site is covered in ancient carvings, many of which have barely aged.

The ancient tomb acts as a calendar that keeps perfect time.

The ruins of an ancient island city built atop a coral reef in the South Pacific are spectacular and strange enough to have inspired H.P. Lovecraft.

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

A series of modernist treehouse hotel rooms grace the outskirts of an Arctic forest.

A medieval abbey featured on 'Game of Thrones' that dates back to the 12th-century.

The easternmost point on the island of Ireland.

This large neolithic tomb, also known as Greengraves, is hidden off a Northern Irish road.