According to the Guanches, the aboriginal people of the Canary Islands, the king of evil lives inside this volcano.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

City law dictates that this mountaintop cathedral containing the heart of a saint is to remain the tallest building in town.

The biggest museum dedicated to insects in North America, one of the largest in the world.

A massive Montreal stadium that has seen nothing but trouble since its inception.

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A mocking tribute to the past and modern leadership of Prague.

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

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

Macabre astrological automaton clock dating to the late 1400s.

Cliffside houses provide a spectacular view from their perch above the valley.

This underground church is topped with a 500-foot cross that is seen by many as a beacon of fascist hubris.

One of the few remaining ancient aqueducts described by Frontinus as 'the most solemn testimony of the Empire.'

The Cathedral of Salamanca has a number of unusual carvings but none so surprising as a modern astronaut.

An ancient Egyptian temple in the middle of Madrid, Spain.

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

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.