Hidden behind a wall for decades, this masonic lodge was only rediscovered during renovations.

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

This unchanged Victorian park is rumored to have been the inspiration behind Peter Pan's Neverland.

When the public was consulted about a new piece of street art, they naturally asked for an enormous metal dragon.

Once the fallout shelter of a dictator, this sprawling bunker is now a combined history museum and contemporary art gallery.

Vortex-shaped aquarium hosts Europe's largest school of piranhas and other ocean creatures.

An ultra-modern diversity park in Denmark has turned an entire city block electric pink.

The whimsical steel spider lurking in the shadows of this suspension bridge shows that engineers can have a sense of humor.

The Andean town where every single building is decorated with a brightly colored frieze.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

This massive crater in the middle of nowhere was used to train astronauts for moon landings.

Strange rock formations tower above the river that snakes through this enchanting Icelandic canyon.

It is still illegal to "quarrel" at this unlikely urban oasis built on top of an electrical substation.

The signs of a long buried road can still be found hidden beneath a London sewer grate.

This landmark church concealed a crypt packed with bones that was discovered thanks to the London Blitz.

Architectural monsters are devouring this palace's every door and window.

This preserved puppy was an adorable beacon of charity.

This historic stone bridge has an entire neighborhood clinging to its sides.

Bronze sculpture celebrating the relationship between Churchill and Roosevelt.

The first declared National Monument in the United States.

A vortex fountain that seems to rise out of the ground.

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

England's "pier at the end of the universe" unites astronomy and contemporary architecture.

This memorial commemorating fallen Swiss Guards of the French Revolution has been called the saddest stone in the world.