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

The medieval "Bearded Man" relief still serves as a clever flood warning marker.

One of the famous Czech artist's lesser-known Prague installations appears to be a glowing fetus affixed to a drainpipe.

A church of bones, decorated with 40,000 human skeletons.

A graceful natural rock formation stands astride the point where the Gulf of California meets the Pacific Ocean.

Wander down a side street dedicated to one of the members of the Beat Generation.

A century and a half of research in the sciences and natural history, still going strong.

A masterpiece in Golden Gate Park by virtue of the artist’s debt.

An elaborate gift from Claus Spreckels is now a piece of San Francisco history.

Is this the most Portland place ever?

A Hungarian pharmacy museum with a box full of mummy powder.

A museum in the childhood house of a medical pioneer.

A series of caves under Castle Hill that once held the prisoner Vlad Tepes, better known as Count Dracula.

A triumphant marble and bronze fountain depicting a 15th-century Hungarian king and his hunting party.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

Giant marble phalluses on the sacred island of antiquity.

These artifacts were discovered during the construction of the airport, with some dating back to the Neolithic period.

This seaside sanctuary was once one of the most important religious sites for women in ancient Greece.

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

Legend says this sacred tree was a gift from goddess Athena.

An ancient Greek monument and a Byzantine church coexist inside this cave.

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

The only ancient site that remains on the south bank of the sacred Ilissos river.

According to legend, this cavern holds the passage that Persephone used to travel to and from the underworld.