Great Moravian sacral architecture is represented by a rich variety of types, from three-nave basilicas (Mikulčice III, Bratislava), triconcha (Devín), simple rotunda without apses (Mikulčice VII), two-apses rotunda (Mikulčice VI), tetraconchic rotunda (Mikulčice IX) and a whole group of one-nave churches and rotundas with one apse. The largest number of churches has been found in south-eastern Moravia. Mikulčice, with 12 churches, clearly dominates among all other localities with the first stone churches built around 800 (a potential 13th church is Kopčany, on the Slovak side of the border). The three-nave basilica from Mikulčice, which has interior dimensions of 35 m by 9 m and a separate baptistery, is the largest sacral building found to date. The high concentration of churches in Mikululčice exceeded the needs of the local population, and so are believed to be proprietary churches ("Eigenkirchen"), known also in Francia. Large churches were also important ecclesiastical centres. The current dating of several churches precedes the Byzantine mission. The churches were decorated mostly by frescoes, but usage of secco is also documented. The authors were probably foreign artists from Francia and northern Italy (the latter indicated by, for example, the chemical composition of paintings in Bratislava and Devín).