Onlookers were fascinated and flummoxed when three human figures appeared in the New York City sky, zooming around buildings and bridges.

A 7-story spiraling 'Tower of Babel' in downtown Buenos Aires is made of 30,000 donated books in all languages.

Cities can sprout from a swath of desert to a bustling metropolis in the blink of an eye - just look at these before and after images of Dubai, Shenzhen & more.

What if the world consisted of nothing but corporate logos and mascots? This epic Los Angeles crime story features some of the world's best-known brands.

Is the "new sport" of pomparkour for real? The video showing insane jumps with ladders is an ad for an energy drink, but shows some interesting feats.

The power of fun is often lost on grownups, but these two public art projects helped put some fun back into the daily lives of UK pedestrians.

Miniature city models are incredibly useful for city planning and architectural design, but they also bring out the kid in just about everyone who sees them.

Parkour is an extremely challenging urban sport that involves big jumps, impressive acrobatics, and a lot of guts. This group captured all that in a crazy jump.

Black Friday . . . are you preparing to battle the holiday shopping crowds? Brush up on your ninjas skills before you go into the battle of the urban ninjas.

Some USB guns are fun, but some are used to strike fear in your cubicle-neighbor's heart. Here are 17 USB "weapons" made by geeks for geeks, from FAIL to fantastic.