These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

It may look like no more than a full-scale model, but every part of this full Space Shuttle stack had a working role in aviation history.

A propulsion engine testbed that paved the way for the Space Shuttle launch sits without recognition at this rocket center.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

The slender brass strip in Prague's Old Town Square was used to tell time from 1652 to 1918.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Macabre astrological automaton clock dating to the late 1400s.