These early churches were no doubt all of very simple construction, the only ornaments being the marble columns and carved work which in some localities were available from Roman buildings. Where these existed the style adopted naturally followed the Roman forms, but in districts where they were absent the style gradually passed into the Romanesque, under the influence of the new elements imported by the Northern invaders. We have seen how Charlemagne attempted to follow a Roman structure in his great church at Aix, and that is a distinct indication of the general tendency. The chief object at this period of transition was to produce an effective internal design, the exterior being invariably very simple. In this also the system by which Roman architecture had been developed continued to be carried out. When the new political conditions of the different divisions of Europe had become somewhat settled, these principles were worked out separately and independently in each country and province, and produced a great variety of styles, all comprehended under the general title of Romanesque. They were in reality all derived from ancient Roman architecture, but by their very variety they indicate the new spirit which was now beginning to express itself. As above mentioned the great desideratum in the eleventh century was a simple form of stone roof. The earlier wooden roof had been found so liable to destruction by fire, that great efforts were now made to provide a fire-proof covering. At San Miniato, near Florence, there still stands a very fine basilica of the beginning of the eleventh century, which shews one method in which this was attempted to be done, and which recalls the mode of construction of the Syrian Churches above referred to. San Miniato is divided into three long bays in its length by circular stone arches, springing from clustered piers, thrown across the nave, each bay being again subdivided by three longitudinal archivolts resting on simple pillars. The above great transverse arches do not, as in the Syrian examples, carry the roof, which is in this instance of wood, and is thus not quite fireproof; but even if the timbers were destroyed by fire, the three transverse arches would tend to bind the structure all together, and prevent further ruin. [Illustration: FIG. 33. SAN MINIATO.] In the church of Notre Dame du Pré at Le Mans in the north-west of France, there is another example of a similar form of roof, constructed in the middle of the eleventh century.