In the days before house numbers, these colorful signs held clues about various buildings' purposes.

The world's oldest Jewish library was founded by Sephardic Jews in 17th century Amsterdam.

This impressive collection of rare books on ancient mysticism inspired author Dan Brown.

A beautifully eclectic mix of architectural styles.

The attic of a four-century-old canal house hides a clandestine church.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

Museum preserving torture methods from the past.

Antique frame collection with 2,400 frames.

What started as a tongue-in-cheek shrine is now a full-blown museum celebrating "The Hoff" and his longtime love affair with Berlin.

The most visited, and possibly most controversial, museum in Germany.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

An artificial hill and apparent calendric structure built in the Early Middle Ages immortalizes a legendary Polish princess.

St. Mary's features one of the most spectacularly decorated cathedral interiors in all of Europe.

The world’s narrowest house makes for an awkward, four-foot-wide living space.