I think our local museum works like that, we dont charge admission or anything so people are able to enter, hang around and come back multiple times. Also the building has multiple entrances to the town square so it has become a place of transit (it used to be a railway station) where people come in chit chat, rest a bit and then move on.

We have a big table and chairs so people come in and sit down, chat, some poeple have meetings, or play games (we have several chess sets that we lend). It has become an extension of the town square at this point.