Around 100,000 bodies are buried below the medieval headstones, many of which mark graves with multiple bodies stacked up to 12 deep.

Macabre astrological automaton clock dating to the late 1400s.

Monument to a suicide protesting the Soviet invasion.

Looming communist pillar with a Czech twist.

A black cat protests the City Guild in Riga's Old Town.

Flamboyant architecture from the turn of 20th century.

The world's largest model of our planetary system.

Sweden's "good old days" painstakingly re-created in a model village.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A marvel of Byzantine engineering under the streets of Istanbul.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

Ancient serpentine sacrifice holder that has stood the test of time.

A fountain standing as a testament to a doomed alliance.

Pilgrimage site for star-crossed lovers.

An ancient Egyptian temple in the middle of Madrid, Spain.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Commonly acknowledged as the only public monument to the Devil himself.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

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.