The ASVi Tram Museum is a serious little museum for Belgium's old Vicinal tram network, the metre-gauge system that once threaded towns and villages across the country. The collection is good, but the real pleasure is riding a preserved tram through Thuin or out towards Lobbes on operating days.
Check the calendar before building a day around it, as museum and tram-running days are seasonal. When the trams are operating, this is one of the most distinctive reasons to choose Thuin over a more obvious Walloon town.