A floating cat sanctuary on an Amsterdam canal.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

"Holy Wisdom" overlooks the city that became its namesake.

A vast Communist-era exhibition space in the Bulgarian capital.

Eastern Bloc nostalgia, anybody?

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A striking symbol of the Bulgarian capital.

A collection of art from Bulgaria's time as a communist state.

This historic black and white monastery is one of Bulgaria's architectural jewels.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

A beautifully eclectic mix of architectural styles.

Step back in time and witness the fall of Constantinople.

A copy of the famous statue can be found in this Florence piazza, along with one of the most breathtaking views of the city below.

Fortified medieval tower house with lovely roof garden.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

Massive galleon from a box-office bomb docked in Genoa.

Legend has it this fountain built to symbolize the Pope’s power hides a strange secret concerning Neptune's manliness.

This bustling Italian plaza is built on the ruins of an ancient Roman amphitheater.

The bomb-ravaged remains of of a colossal Neptune.

This bronze boar's snout has been rubbed to a golden sheen by visitors seeking good fortune.

Secret refuge and museum of the Duke of Florence.

Over 50 exquisite hand-painted Renaissance maps decorate a Medici storage room.