The Tavern is a very large building that requires a lot of materials to build. It is used in a lot of the more advanced Quests, so at some point you will want to build at least 1 if not 2.
Because of all the materials required, plan ahead before purchasing the Tavern or you might wind up with it sitting there unbuilt for a while!
Fortunately we've put together some tips to help you -
Check Neighbors for a Large Library. These will drop Knowledge each time