The oldest brewery of the world if the "Bayrische Staatsbrauerei Weihenstephan", which means "Bavarian state brewery Weihenstephan", which was founded 1049. However it is not sure that the document was not a fake and that the brewery was actually founded later. During the Middle Ages a lot of brewery were founded. Till today in Germany beer may only be brewed according to the "Reinheitsgebot" (German beer purity law), which was passed in 1516. It says that beer may only contain malt, water and hops.