AHHAA! as in, 'Oh, that's how that works!'. One of the city's biggest attractions by far, this vast, super-modern centre invites people of all ages to discover - or rediscover - just how fun science can be. Here you can spend hours trying out the over 170 riveting, often wacky hands-on exhibits. These will have you biking across a tight-rope and losing yourself in mirror maze. Over 20,000 inhabitants await you in the Hall of Nature. Be absolutely sure to check the schedule for the amazing Science Theatre shows where things bubble, smoke and go bang. The cutting-edge planetarium shows (these cost extra) are also well worth checking out.