In Florence's great Duomo, a 26 foot fresco honors a mercenary famous for attacking Florence.

Renaissance hospital featuring a rotating door into which unwanted babies were dropped.

A lover's walk between hilltop towns, decorated with graffiti love notes.

The bomb-ravaged remains of of a colossal Neptune.

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

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

Old batteries and frog skeletons reside in this lakeside monument to Alessandro Volta.

A 14th century bridge built as a fortress, where the devil lurks on one of its towers.

Bordered by forest on three sides and the ocean on the other, the Great Dune of Pilat is the highest sand dune in Europe.

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

Protecting the dead from opportunistic body snatchers.

360° views of the city plus five floors of optical illusions and hands-on science.

The final resting place of soldiers' loyal canine companions.

A six-ton wedding present for the King of the Scots.

The most loyal of little dogs, or a Victorian era publicity stunt?

The tomb of one of Scotland's bloody historic villains is a magnet for bumbling desecrators.

Stroll through Welsh history in a village of reconstructed structures.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

Catacombs turned marketplace.

The monster at the center of the Darwin Center Spirit Collection.

Eighty million natural history specimens call this gargantuan museum home.

Repository for more than 22 million pickled specimens.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

A historic London cemetery now serves as a nature park incorporating gravestones & memorial statues.