 Circular towers are uncommon in England, but occur throughout the Early Medieval period in Ireland.Polygonal towers were often used on crossings and occur in France, Germany, Italy and Spain such as that of the Old Cathedral, Salamanca, which is covered by a dome supported on a ribbed vault.Smaller churches sometimes had bell-gables instead of towers, a feature which, according to some authors, is characteristic of the simplicity of much architecture in the Romanesque style.