Carnegie Library of Pittsburgh: Free public library, with a plethora of things to do besides borrowing books, videos & movies of course! They offer various free language classes, events for kids and adults alike, volunteer opportunities if you’re so inclined: https://www.carnegielibrary.org/
Toy Library, Pittsburgh: is a volunteer-run cooperative play space and toy library. It provides a safe, imaginative and playful environment for young children. One of the best places for kids on rainy days: http://pghtoys.org/
Carnegie Museums: Interesting exhibitions, events & for making the most of cold freezing days: https://carnegiemuseums.org/
Unusual Museums around town:
https://www.discovertheburgh.com/unusual-museums-in-pittsburgh/