The bears of Bern have been a city highlight for over 500 years.

The prototype for all Nazi concentration camps.

Macabre astrological automaton clock dating to the late 1400s.

The topiary maze at the Habsburg hunting lodge.

Baroque celebration of the end of the Great Plague of Vienna.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

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

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

A little sculpture with a large wardrobe.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Roman ruins top white travertine terraces formed by ancient hot springs.

A marvel of Byzantine engineering under the streets of Istanbul.