These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

A spectacular cave and a beguiling lake.

The hallucinogenic center of the ancient world.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

Erotic art covers the walls of the largest ancient pleasure palace.

This monumental fountain has moved around the city multiple times.

Go inside to really appreciate this 500-year-old technological masterpiece.

This Venice bookstore has resigned itself to constant flooding by keeping its books in bathtubs and boats.

This community on a small Venetian island has taken to painting their houses in bright neon hues.

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

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

An ossuary built in 1210 to collect bones from the Ospedale Maggiore of Milan.

A rather vulgar example of the transition from Latin to the Italian vernacular.

A master of trompe-l'oeil creates a stunning, tourist-fooling dome out of a flat ceiling.

This artistic fountain display pays homage to this area's theatrical history.

The bears of Bern have been a city highlight for over 500 years.

One of a series of no-purpose kinetic artworks by Swiss sculptor Jean Tinguely.

A constellation of golden cobblestones shows the names of local children born under a full moon.

Florentine Renaissance style building in Switzerland, home to the world's largest taxidermy Great White Shark.

Artworks by loners, prisoners and the criminally insane.

The celebrated eyesore created by starry-eyed sweethearts.

Paris' linguistic guide to the international language of, yes, love.

This monumental work of art symbolizes the coming together of a previously divided city.