A labyrinth of ancient tunnels hidden below the city holds the ruins of 2,500 years of history.

The underground sanctuary of a mysterious ancient cult.

A detailed pachyderm supports Rome's smallest Egyptian obelisk.

The only "Egyptian" pyramid in Europe and the legendary tomb of Remus.

Rome's semi-secret peephole vista is also a former Crusader stronghold.

Gods clash with machines in a power plant regenerated as a museum.

This ritzy Italian market is built around a statue of an unforgiven heretic who was burned for his belief in an endless universe.

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

A patriotic medieval knight in driven-nail armor raised money for widows and orphans of WWI.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

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