In the 10th century the establishment of churches and monasteries led to the development of stone architecture that elaborated vernacular Roman forms, from which the term "Romanesque" is derived. Where available, Roman brick and stone buildings were recycled for their materials. From the tentative beginnings known as the First Romanesque, the style flourished and spread across Europe in a remarkably homogeneous form. Just before 1000 there was a great wave of building stone churches all over Europe. Romanesque buildings have massive stone walls, openings topped by semi-circular arches, small windows, and, particularly in France, arched stone vaults. The large portal with coloured sculpture in high relief became a central feature of façades, especially in France, and the capitals of columns were often carved with narrative scenes of imaginative monsters and animals. According to art historian C. R. Dodwell, "virtually all the churches in the West were decorated with wall-paintings", of which few survive. Simultaneous with the development in church architecture, the distinctive European form of the castle was developed, and became crucial to politics and warfare.