In the shadow of a former battleground, the resting place for nearly 2,000 soldiers who died in World War I.

A moving memorial to the fallen and missing from WWI trenches.

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

A 14th-century fortified keep showcases the masterpieces of an ingenious 20th-century clockmaker.

The oldest standing Byzantine church in Athens is tucked within a monastery in the middle of an upscale shopping district.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

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

The haunted reputation of these abandoned Colorado train tunnels is probably not helped by the terrifying spiked fence.

Its tremendous toad is actually a five-story museum and viewing platform.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

A limestone wonderland of water and subterranean secrets.

One fisherman has used his love of pebbles and shore to create a crazy garden of rocky art.

A vintage penny arcade hidden in the back of a fun fair-themed bar.

The rotting skeleton of a shoreside fun fair that was destroyed by fire and storms still haunts the Brighton ocean view.

Catacombs turned marketplace.

Eighty million natural history specimens call this gargantuan museum home.

One part local history, 99 parts gruesome haunted house.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.