Romanesque architecture developed in Europe between the 11th and 12th centuries, with some proposals dating it back to the 6th century. It was characterized by thick walls, small windows, round arches, barrel or groin vaults, and heavy, stable construction. The style varied regionally but emphasized stone construction and reflected Roman, Germanic, and other influences. Major building types included churches in the form of basilicas or with Latin crosses, monasteries with churches and other buildings arranged around a cloister, and fortified castles.