A little sculpture with a large wardrobe.

A rare example of World War I trenches from the British front.

This abandoned Belgian fortress is purposefully being left to nature.

From Tintin to the Smurfs, Europe's greatest graphic icons are celebrated in a grand Art Noveau gallery.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Climb inside an iron crystal magnified 165 billion times its normal size.

Lavish royal estate punctuated with heated greenhouses.

Each spring, a dreamlike carpet of bluebells overtakes the forest floor.

Gladiators once walked this ancient, subterranean passage.

The ruins of this ancient fortification wall sit in the middle of a quiet, residential intersection.

These caves secretly held national treasures during World War II.

An often overlooked ancient site in downtown Athens with substantial history (and nature).

This graffitied 19th-century building was a prototype of European industrial architecture.

Where commuters walk through remnants of an ancient Greek necropolis.

This ancient hydrological marvel is now the base of a modern outdoor cinema.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

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

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

A supersonic jet stands on a pedestal in this rural village as a monument to military aviation.

This building has two facades of clashing architectural designs.

Massive, unfinished broadcasting station stands as a monument to the fall of communism.

This apartment is a true time capsule of local life in Bulgaria during the Soviet regime.

One of the largest mines in Bulgaria is now home to a vast museum more than 100 feet underground.