a profound effect on the decoration of buildings. The existence and continuance of local rather than unified rule meant the construction and continued existence of many Romanesque civic buildings, and a large number of cathedrals. A great many religious buildings of this period remain, many of them little altered. Other buildings include fortifications, castles, civic buildings, and innumerable domestic buildings that are often much altered. Characteristics Large churches often have basilical form, with a projecting apse. Some large churches have projecting transepts as at Pisa Cathedral. Towers are freestanding and may be circular as at Pisa. Windows are small. The façade takes two forms, that which coincides with the basilical section of nave and aisles, as at Pisa Cathedral and that which screens the form, such as San Michele, Pavia. Dwarf galleries are the prevalent form of decoration on the façade as at Pisa Cathedral. A number of churches have facades and interiors that are faced with polychrome marble, as at San Miniato al Monte. The rest of a brick exterior was generally left undecorated with some notable exceptions including Pisa Cathedral. Portals were rarely large and were square rather than round, as at San Miniato al Monte. Decorative tympanums, where they exist, are mosaic, fresco or shallow relief, as at San Zeno, Verona. Shallow relief carving in marble was a feature of some facades, as at San Zeno and Modena Cathedral Ocular and Wheel windows are commonly found in facades, as at San Zeno and Modena Cathedral. Portals are sometimes covered by an open porch supported on two columns standing on the backs of lions at San Zeno, Verona. Internally, large churches generally have arcades resting on columns of Classical form. There is little emphasis on vertical mouldings. The wall surface above the arcade was covered with decorative marble, mosaic or fresco. Galleries such as that at Pisa were uncommon, but occur in convent churches as nuns' galleries. Open timber roofs prevailed. Ribbed vaults, when used, are large, square and domical, spanning two bays as at San Michele, Pavia, and Basilica of Sant'Ambrogio. The crossing is often covered by a dome, as at Bari Cathedral and Pisa Cathedral (where the dome is oval and of a later date). The choir may be above a vaulted crypt, accessible from the nave or aisles, as at San Zeno, Verona. Freestanding polygonal baptisteries were common, as at Parma Cathedral and the Baptistery