These Pre-Columbian petroglyphs contain representations of birds, deer, hunters, and even some early Native flute players.

Life-sized sculpture of a blue whale made of hand-recycled plastic trash.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Colorful and chaotic stacked hotel in North Holland.

Dine on food tied to Viking history and legend at this subterranean Stockholm spot.

Stockholm's deepest subway station is also a stunning ecological wonder.

The library's graceful rotunda is like a bibliophile's temple.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

This palatial spiral staircase was so unusual the name "snail" was given to the noble family who built it.

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

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

At this Denver landmark, the meals are compulsory, the sopapillas are complimentary, and the insanity is everywhere.

This Chinese-style quartz sundial was saved in its final hour.

Golden Gate Park's historic collection of plants.

This private residence was the template for one of the most beloved television homes of all time.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

Relics of the 1894 Midwinter Exposition continue to delight visitors today.

A local student's chance encounter with Keith Haring led to the creation of one of Europe's largest murals.

Many famous English poets including Elizabeth Barrett Browning are laid to rest at this Swiss-owned cemetery in Florence.

Memorials at a Florence railway station remember the citizens who were deported from Italy and sent to extermination camps.

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.

Drink wine handed out through a window as part of an age-old tradition.

This private skyway is filled with art and was expanded explicitly so that Hitler could appreciate a river.

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