This psychedelic tromp l'oeil seems to be beckoning drivers to crash into a wall.

This titanic steel chain linking two buildings was installed without permission but instantly beloved.

The world's largest fire hydrant is supposedly tornado-proof.

Dr Barnes' $25 billion private collection of art and arboretum.

Huge masonic hall in Philadelphia with lavishly themed rooms.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

The curious underground history of keeping Paris clean.

This still-celebrated home was a radical architectural experiment in 3D De Stijl.

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

Light bulbs, scrap wood, and tinfoil comprise this homemade throne of the gods.

The first purpose-built art gallery in the United States is once again open as a center of craft arts.

The highest point in North Carolina and the United States east of the Mississippi River, Mount Mitchell is named after argumentative explorer Elisha Mitchell.

Who needs fancy modern water slides when this giant North Carolina rock works just as well?

The "last unrestored grand mansion of Savannah" is now a cramped, mouldering maze of antiques.

This quirky curiosity shop takes its cues from the world's bazaars.

Architect Le Corbusier built his friend a cubist house to match his impressive collection of cubist art.

Monument to a suicide protesting the Soviet invasion.

The most visited, and possibly most controversial, museum in Germany.

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

Built to repay the sins of the father, this church is home to one of the most valuable works of Western art.

In the world's oldest university is a stunning 17th century anatomical theater carved from spruce.

Now an entertainment complex, the Lingotto building was once an avant-garde auto factory with a test track on the roof.

A lover's walk between hilltop towns, decorated with graffiti love notes.