The tithe system was pretty brutal, and one of the reasons why tithe barns can look a bit like fortresses is that they were deliberately constructed to symbolise the feudal power they embodied. The Monastic system was especially oppressive, because they represented religious power as well as secular. In St.Albans, where I live, the abbot confiscated all the local millstones so that everybody had to bring their grain to the abbey mill, the perfect way to control the tithe. The millstones were used to pave the floor of the abbey church – also heavily symbolic, I think. During the Peasants’ Revolt, the rebels attacked the abbey and ripped up the floor. No wonder a barn like this looks like it was built to be defended!
You’d love Grange Barn at Coggeshall in Essex,which is even older – 12th century. Doesn’t look anything like as impressive from outside, because it had to be completely restored when the National Trust got hold of it in the 1990s, but the timber structure inside is beautiful.