This beautiful park on the outskirts of Rome protects the ruins of two colossal ancient aqueducts.

Sitting on an Italian hilltop is this surreal fortress built by the mad inventor of electrohomeopathy.

A visionary Italian architect created an impressive cluster of concrete structures for a family's private tomb.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

The first tunnel to be dug beneath a river, repurposed as an art and museum space.

A 19th-century subterranean reservoir repurposed as a contemporary art cave.

There are two dozen tanks just sitting in an open field in Lower Saxony.

Between Neo-Pagans and Neo-Nazis, these strange rock formations have a curious cult following and a very strange history.

An intricate and amazing house built by architect Karl Junker.

The history of German architecture is explored across this fairy-scale mini-city.

These beautiful objects represent beautiful ideas.

The abandoned mine where American troops discovered a treasure trove of art and artifacts hidden by the Nazis.

A century-long search for a church that was never there.

As lake waters recede, a German village reemerges after more than a hundred years.

Medieval ruins on a tiny island amid a flooded lake offer romantic respite to lovers seeking privacy.

This unique Renaissance castle was turned into a home for Nazi occultism.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

This ancient hydrological marvel is now the base of a modern outdoor cinema.

This mystical orb covered in strange symbols is thought to have been used in ancient Greek magical rituals.

An ancient octagonal weather station named for the eight Greek gods of wind.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A genuine Little Shop of Horrors.

Where the U.S. government kept its actual treasure, before Fort Knox.