In France the plan resolved itself into an open semicircular colonnade with a passage intervening between it and the outer wall which followed the outline of a series of small apses. These formed an harmonious cluster, and became a type which was matured in the thirteenth and fourteenth centuries. Those belonging to the Romanesque period, however, had a distinct and constructively excellent character which has rarely been subsequently surpassed. Among the best are those of Notre Dame du Port at Clermont, St. Etienne de Nevers, and St. Sernin at Toulouse. In France towers were generally placed at the West end of the church, while in England and Germany the usual way was to build them at the junction of the nave and transept; in Italy they were often detached from the main structure. They were characterized by simple solidity; the openings being few and the detail bold; the angles were strengthened by stout piers; the roofs were either of timber or stone, according to the nature of the materials in the localities in which they were erected, and they were usually lighted by the round-arched double window. This round arch, ornamented with a few simple mouldings and reposing upon short sturdy columns, forms a constantly recurring feature in the composition of the several parts of Romanesque buildings. The corridors which surrounded the square courtyards adjoining churches, and connected them with the dormitories, refectories, and other apartments of the clergy, are called cloisters. They differed but little from the Roman “impluvium” and the “atrium” of the basilica, the changes consisting chiefly in the addition of raised sills separating them from the court, and in their being usually vaulted instead of carrying timber roofs. The series of arcades forming them were treated in many ways, and the detail admitted of much elaboration and variety, as may be seen in the many remarkable examples throughout Europe. The cloisters of St. Paul’s, at Rome, and the atrium of St. Ambrogio, at Milan, form very interesting historical links between the Roman and Romanesque styles and are very beautiful specimens of their kind. It had been the custom during the struggling period of the early Church to bury the bodies of saints in subterranean chambers called crypts, a word derived from the Greek verb “to hide”; subsequently these became component parts of all churches, serving as places of interment and for the occasional celebration of masses. Their masonry was necessarily of the massive character required for the foundation of the piers of the church above, consisting generally in a grouping of columns sustaining a heavy vault. [Illustration: CHEVET OF NOTRE DAME DU PORT AT CLERMONT. (_From Chapuy._)] The crypt of St. Eutrope, at Saintes in France, may be mentioned as one of the best examples, the pillars being richly carved, and the ribs of the vault of great boldness and strength.