This intriguing Bronze Age artifact spent centuries hidden within a Welsh faerie hill.

The gigantic skull of a long-extinct species that once roamed the forests of England and Ireland.

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

A wonderfully kitsch bookstore the size of a supermarket.

This Greek temple, open only an hour a day, was the site of a war of tastes between an architect and an artist.

This modern arts center is built around a gem of late-Baroque architecture.

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

This narrow Ghent alleyway is an officially sanctioned street art tunnel.

Christ's blood preserved in a Belgian town.

This unattributed sculpture in Amsterdam is hiding in plain sight.

Famed for its pie, this eatery has a hidden tunnel that allowed Catholics to secretly walk to church during the Reformation.

This cheese shop also houses a museum devoted to Dutch dairy.

One of Amsterdam's narrowest houses is located right across the canal from its widest.

A beautifully eclectic mix of architectural styles.

This large copper bolt represents the benchmark for measuring sea levels in most of Europe.

This massive mural by famed pop-artist Keith Haring was hidden for almost 30 years until its 2018 rediscovery.

Amsterdam's former hotspot for public executions and dissections.

This pirate-broadcasting-tower-turned-restaurant played a rebellious role in the history of Dutch television.

This unusual elevator doesn’t stop or slow down.

A unique collection of gilded age mechanical pianos.

The last of Amsterdam's original sea level markers remaining in place.

A set of seven houses, each built in a style that represents a European country.

Where royalty waits in the height of luxury.

A unique work of automotive art calls this shopping center home.