Kids run on the roof and climb trees at 'the world's best kindergarten'

San Francisco, California may have Brightworks School - the fire-filled experiment zone where kids sometimes learn the hard way - but Tachikawa, Japan has Fuji Kindergarten.

The giant open-air building, built in 2007 as a complete circle, encourages kids to run around on a rooftop boardwalk, climb nearby trees, fall down, and move freely between rooms once they dust themselves off.

For architect Takaharu Tezuka, that's about as close to perfection as you could get.