Huge stairway leads to this massive gallery.

Inside this building is another country within Rome, a sovereign entity without a physical territory.

This basilica is dedicated to two saints, one of which is known more for his famous quote.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

A magnificent collection of imperial armor and weaponry.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

The Habsburgs' royal collections of art and wonders.

The final resting place for the remains of 143 Habsburg royalty.

A mechanical clock built in 1914, with a rotation of 12 historical figures on its face.

Baroque celebration of the end of the Great Plague of Vienna.

These two 15th-century metal rods allowed people to check if they were swindled or not.

In the middle of a Vienna square, Roman ruins dating back some 2,000 years are on display.

A gigantic collection of teeny, tiny books.

This mysterious but iconic tapered tower appears in many Azeri fairytales and legends.

A unique museum dedicated to culture and artistry of carpet weaving.

The building's fluid, wavelike walls are a true feat of architectural ingenuity.

A lively circle of dancers in the Georgian capital commemorates an ancient rite of spring.

When the Soviets destroyed the historic Armenian monastery they somehow left its bell tower intact.

A gleaming white and undulating tower marks the border between Georgia and Turkey.

Step back in time and witness the fall of Constantinople.

Climb a set of vertiginous stone steps to the top of this impressive ancient edifice.

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

This former Imperial summer home was the venue for a royal slap that once echoed 'round the world.

The ornate miniature mansions were built for Istanbul's feathered residents.