I often nanny for 3 kids at a time, so going places that cost 5+ dollars per child is not really a good option. For free, this place is AMAZING. Not only is the entire thing interactive, but it is widely ranged for kids up to age 5. One downfall, at least during the summer, is that you cannot have older children in with you. So if you have a 6 year old and 3-4 year old, it does make it difficult. Otherwise, I think Storyville is a great place to learn and interact!
This was a great find for our 19 month old. You can begin bringing infants here, and the play area is partitioned, keeping age appropriate kids in separate areas. There are dress up areas, a kitchen area, and reading area, a stage with costumes to put on plays, and much more. Best of all it's free! A hidden gem in a library, just 20 minutes north of Baltimore.
This place in fantastic. Every time I go, I can't believe that they do not charge a fee! There are so many different things for the kids to do. Ladders, a staircase, grocery store, kitchen, books, dress up, a garden, a section only for non-walkers, etc!! I suggest getting there in the morning right when they open. In my experience they start to get busy around 10:30am.
Storyville at the Rosedale Library is essentially a mini-children's museum ("interactive early literacy learning center") inside of a public library . The space is very clean and includes a seven play areas, including one specifically for babies. My kids love visiting every time we go!