Museums some are kid friendly, zoos, aquariums, arboretums or botanical gardens, kid friendly places like trampoline parks, play gyms.
My 4 MO's favourite location is the garden store. She loves looking at all the plants. Which country are you in? In mine , where it's way too hot in the summer but nice now. I am planning on going to walk in the shopping malls early in the morning in the summer. It's not exactly fresh air, but it will get us moving and there are washrooms with baby changing facilities there.
I have taken my son to ikea and let him explore all the rooms.
Libraries are great. Surprisingly most have toys and grouos to play.