A collection of art from Bulgaria's time as a communist state.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

An architectural marvel that spans the Arda River, and has stories of a haunted past.

This huge metal monument is slowly being stripped to its concrete skeleton.

An Art Deco Icarus statue adorns this abandoned gem of Yugoslav Modernist architecture.

This truly palatial work of Communist-era architecture now sits crumbling on a Croatian beach.

Space-age monument to an early 20th-century uprising.

Crossing a suspension bridge above a forest is the only way to reach this 12th-century monastery.

The deadliest diving spot in the world is also a stunning geological marvel.

A tribute to the 20th-century ball that cast a spotlight on Mexico’s LGBTQ community.

These unusual paintings give thanks to the saints and deities who granted people favors and miracles.

It's believed this golden brick is part of the legendary lost Aztec treasure.

Diego Rivera hid various people and symbols in his first large-scale mural project.

On a cornerstone of the City Museum is the head of a monstrous serpent stolen from an Aztec pyramid 400 years ago.

A small pack of an ancient, hairless breed of dog once believed to guide souls through the underworld lives on its grounds.

A Volkswagen Beetle decorated with millions of beads connects Mexico's past and future.

The ruins of the bathhouse used by the ill-fated last Aztec emperor still lie in Chapultepec Park.

This extraordinary art museum is like a secret world on the edge of Mexico City.

This crumbling Art Deco movie palace in Mexico City has been abandoned for two decades.

A scientific repository of goiters, boils and other ailments throughout Mexican history.

A museum in the former home of Marxist revolutionary Leon Trotsky.

Diego Rivera's massive tiled fountain and failed infrastructure project.

66,000 pieces of art, donated by one of the world's richest men.

One of the city's few vendors selling the Sierra Norte's ancestral beverage lies within a hidden farmers market.