A decaying, yet still functioning, work of communist architecture.

A massive cave once a secret military base is now home to thousands of bats.

Rebuilt several decades ago, its striking murals prevent it from being reconsecrated as a church.

An homage to the medieval rulers of Bulgaria.

These cascading falls resonate throughout the Bulgarian forest.

Rock carving created 1,300 years ago 75 feet off the ground.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

UNESCO-protected ancient burial ground.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

An ancient Thracian city where fire rituals were practiced on the largest cult altar in Southeast Europe.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

This historic black and white monastery is one of Bulgaria's architectural jewels.

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

Bizarrely shaped rock formations in northwest Bulgaria come with equally bizarre legends.

An abandoned saucer-shaped monument in the Bulgarian mountains.

Originally meant to hold a statue of King William IV, this support sat empty for years. Today, it hosts a rotating cast of public artwork.

Chelsea's soldiers were given strict orders when crossing this historic bridge.

Formerly known as Saville Theatre, this mid-20th-century entertainment hub includes an ornate frieze.

The Great Fire of London and the regulation of one-way streets both started in this alley.

This pub boasts a curious history and may have inspired a Dickens character.

Legend says these colorful, invasive residents are the descendants of birds released by Jimi Hendrix.

The bridge is a secret gallery of discarded gum that has been transformed into miniature masterpieces.

This former medical factory gives home to cutting edge arts in the shadow of a gas works.