The National Museum has put together a small playground/play area for toddlers (up to 4 years old I think). It's called the Murmurs Playground, I think. It's pretty neat if you're wondering what to do on a rainy day with your young kiddos. It's got little tunnels, a ball area, comfy bean bags and an area for drawing with crayons. Total time spent there: 45mins to 1 hour. :) It's in the basement of the National Museum and it's free!