A castle perched precariously over the Crimean Sea.

Brussels' favorite peeing boy has a sister.

A little sculpture with a large wardrobe.

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

One of Antoni Gaudí's least-visited works, an homage to Catalan patrimony that mixes neo-Gothic with Modernista forms.

An unusual collection of self-made musical instruments and unique noises.

This amazing ancient cave was kept secret for seven years to protect it from the public.

The art museum is decorated with creatively remodeled pre-Nazi swastikas.

Climb to the top of its spiral spire for spectacular views of Copenhagen.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

Pre-Nazi swastikas adorn the sculpted pachyderms flanking this brewhouse portal.

The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

Elevated freight railway turned wildly successful urban park.

What once sat in the world’s spotlight is today a largely disused ghost complex.

The 1852 novel "Uncle Tom's Cabin" lends its name to a subway station, a street, and several shops on the edge of Berlin.

The famous artist couple lived and worked here, in two different houses separated by a bridge.

A long-buried ancient ruin unearthed right in the middle of the city.

People have been living in the cave houses on this Italian hillside since the Neolithic era.

A cave in southern Italy adorned with thousand-year-old Biblical frescoes existed in obscurity until fairly recently.

The remains of an ancient city-state along the Silk Road.

This "tower of death" has acted as an observatory, a religious hub, and an executioner's lair.

Ancient barriers wrap around what was once an important stop along the Silk Road.

Light still pours into the ruins of this ancient Islamic observatory.

Once a bustling fishing port, this semi-ghost town is now more than 90 miles away from the shore.