This looks like an ultra-modern playground, but it's actually an astronomical observatory in Jaipur, India. It was built on orders from Maharajah Jai Singh II in the early 1700s. Jantar Mantar, which means calculation instrument, is the largest of five observatories the Maharajah had built to explore and measure the heavens. Read more about it and see plenty of pictures at Kuriositas. Link -via the Presurfer
(Image credit: Flickr user ComradeCosmobot)