The ornate structure is part of a building boasting more marble than the Vatican.

This Arctic mining town is home to a cat that's spent years masquerading as a fox.

Legend says this mysterious stone head belongs to a woman who was petrified by an alchemist.

Wander among the abandoned ruins of this once-powerful medieval town.

While only two of the ancient buildings at this site are actually churches this was one of the earliest Irish pilgrimage sites ever.

These abandoned vessels are destined to be reclaimed by the forest.

This ruined 15th-century hermitage is steeped in myth and mystery.

The runoff from these fiery cliffs sends red water flowing into the sea.

The shape of this old salt factory complex was inspired by the course of the Sun.

This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

The ruins of a medieval monastery built on a perilous slope.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

A patchwork of ruins from various civilizations in one of the world's oldest continually inhabited cities.

One of Europe's largest supercomputers is housed inside of a disused chapel.

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.

Step inside the first house designed by Catalan architect Antoni Gaudí, considered to be one of the first Art Nouveau buildings.

A network of concealed passageways lies within a busy London Underground station.

A science fiction-inspired apartment building designed by a famous Spanish architect.

This 170-year-old Swiss guesthouse built into the side of a mountain is best accessed by a cable car.

An abandoned railroad tunnel is now filled with bioluminescent bugs.

Known as the leaning temple, the sacred structure has somehow developed a severe nine-degree slant.

A dreamy mausoleum honors Persia's most famous poet.

This iconic hilltop church doubled as a lighthouse in the 19th century, guiding ships into the port of Valparaíso.

A breathtaking flower tunnel bursts with beautiful golden blossoms.