A historic Christian shrine nestled within a spectacular natural cave.

This enormous censer uses a pulley system installed over 400 years ago.

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

The verdant mossy ruins of a Franciscan monastery lie in the remote Sintra hills awaiting exploration.

A hidden barn-sized rendition of Grant Wood's most famous, and most parodied, painting.

One of just a few cities in the world to base their center of government on an island. Others: Paris and Osaka.

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

A tiny church on a man-made island in the Adriatic.

Gargoyle head that brings good luck.

An ancient knight and a symbol of the city's freedom.

A musical instrument played by the sea.

The big toe of this towering monument to a Croatian national hero is worn from years of superstitious rubbing.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

This restored Portuguese cafe may well be the most beautiful place in the world to grab a Big Mac.

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

Where commuters walk through remnants of an ancient Greek necropolis.

This famous archeological mystery may be an ancient example of movable type.

1,500 Commonwealth servicemen of World War II are buried or commemorated in this cemetery.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

Baltimore's classic clock tower was once topped by a rotating, 20-ton medicine bottle.

Maryland's first (and last standing) toll house on America's first federal road established the state as the "Gateway to the West."

Built by the patriotic residents of Boonsboro in a single day.

Captain John Smith thought these cliffs were amazing in 1608 but sharks thought so 20 million years before him.

Scattered throughout London are ancient remnants of the city's former bounding wall.