The Large Library is gorgeous, but it does not look like the store icon, we've asked the developers to change it to be the correct graphic, hopefully they will soon! ! It is available at any level If you are a Resource Angel and have 300 to spend, you will want to add this building to your land as it drops Knowledge each time a Neighbor clicks on it when visiting.
The Large Library had it's timer reduced from 24h to 9 hours in September of 2017. This was indeed a welcome change!
The Large Library has no upgrade levels.
You will need to gather Paper from your own Paper Workshop or get it as a random drop from Neighbors in order to craft the Books needed for build req's. You will also need +3 Books to begin production
Visiting Tips: if you are going to click on a Neighbors Large Library, please click it first so your visit can be declined. You will still get the Knowledge and anyone who visits after you can get it as well!