Now harmless, this looming post struck fear into the heart of medieval troublemakers.

A collection of intricate sculptures so small they have to be seen through a microscope.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

A massive natural rock arch gives the Tuscan mountain its own window to the sky.

The 1936 Summer Olympics site is a crumbling remnant of sportsmanship and a history its host country would like to forget.

This whimsical statue dumps water on its head to symbolize knowledge flowing into his brain. Or maybe booze.

A walkable map of the world, made from soil and stone by one man.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

Southern Italy's spinning top village.

The world's only flying boat museum honors a small Irish village that sent 20th-century aviation to new heights.

A collection of housewares from recent Irish history adjoined by a tower from ancient Irish history.

Petrified footprints of one of the very first vertebrates to walk on land.

An outstanding and haunting glimpse of the horrors of the Great Famine of Ireland.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

A standing relief of a Norman knight whose posture marks him as a Crusader.

This 30-foot pile of rocks may be the grave of a mythological Irish queen.

This giant urban staircase was built to keep the city's brave fighting men from getting waylaid in the red light district.

A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

A spooky juxtaposition of caves and graves gives this legend-filled cemetery a particularly haunting vibe.

On rare days, this abandoned castle's gatekeepers open its doors, revealing the eye-popping splendor hidden inside.

The world's tallest bridge is also possibly the most elegant.

The collection contains over 25,000 items and details the painful dental practices of the past.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.