This star-shaped artillery fort protected the mouth of the Thames from the 16th century to the Second World War.

The biggest and deepest Cold War bunker open to the public can be found in southeast England.

Known as the "Fat Man of Maldon," Bright was a larger-than-life figure.

Constructed during the 7th century this is one of the oldest largely intact Christian churches in England.

This charming, narrow-gauge railway in the Thames Estuary is sometimes referred to as the "Train to Nowhere."

A perilous medieval road leading right into the sea.

This striking sculpture of Icarus honors Greece's fallen flyers.

This small 16th-century church in Athens is almost entirely surrounded by a modern building.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

An ancient octagonal weather station named for the eight Greek gods of wind.

Gladiators once walked this ancient, subterranean passage.

A sharp sculpture made of thousands of pieces of jagged glass.

Where commuters walk through remnants of an ancient Greek necropolis.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

There are many Byzantine-era churches still standing in Athens, but this is the only one with a 2,500-year-old column rising through its roof.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

A statue commemorating a Polish dog who took his role as man's best friend very seriously.

This Polish cave has housed a dragon, a brothel, and an enduring legend.

Beneath Kraków Old Town's main square lies a hologram-filled medieval market vampire graveyard wonderland.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

This extensive collection covers thousands of years of Polish military history.

The Polish capital has had a deep connection to its guardian mermaid for almost a millennium now.

A tribute to the Polish insurgents who fought in the failed attempt to end their city's Nazi occupation.

Thousands of slain Soviet soldiers are buried within the shadow of this enormous obelisk.