are 2 and 3 year olds too young?

I agree with everyone. They woukd love it,but it might be stressful keeping an eye on them.

I just took my 3 year old son there a few weeks ago and he had an absolutely ridiculously AMAZING time!!! I would do a one to one ratio of adult and child (under 8 years old). There are endless possibilities of things to do. The reason that I suggested a 1 parent to 1 child v is there are places that you don't want a smaller child going with out an adult right next to them!!! Think crawling through a "open" metal tunnel, 3-4 stories up and there are places that a small child could potentially crawl through and fall. Also there are an amazing amount of tunnels, passage ways, slides, things to climb and a huge fish tank!!! It's one of the most beautiful, innovative, exciting, scary and inspiring places that I have ever been to! A couple of extra things to think about. Bring food and snacks ( I don't think that you can bring them inside) because you will spend hours and hours there and the food is not very good! Bring knee pads and work gloves for adults. Hand sanitizer, water and......

2 and 3 year olds would need strict supervision

I think so. Kids that young can get lost pretty easily in there.

There's nothing preventing then from coming, but there's also nothing soft in the place, so it'll depend on how well they can take a bump I'd say. I probably would've enjoyed City Museum most around age 6 or 7