The eclectic observatory castle of a 19th-century astronomer and explorer.

A 16th-century fountain marks the site of a lost medieval cemetery once filled with mass graves.

A series of abstract, silly sculptures represent the works of a great modern classical composer.

How did a French journalist’s grave become the sexiest statue in the cemetery?

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

Museum devoted to the artificial language of Esperanto.

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Op-art architecture designed for happiness.

Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

The Habsburgs' royal collections of art and wonders.

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

Handsomely crafted representations of our round planet.

20-foot tall lamp mumbles Swedish to celebrate the holidays.

There has been an astronomical clock on this spot since the 14th century.

Lyon, France is home to two remarkably preserved Roman theaters, one dating back to 15 BCE.

Hundreds of hidden passageways weave through the old quarters of Lyon.

The small peaceful island off the Venice tourist circuit is where the city began more than 1,500 years ago.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Venice's island of the dead.

This ancient Roman bridge and aqueduct still stands as a wonder of classical construction.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Natural history museum celebrating biodiversity with a parade of taxidermy animals.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

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