The cities, in the thirteenth century, began to exhibit a stately architectural character. The building of splendid cathedrals and monasteries, which began two centuries before, now gave employment to such a large number of architects and stone-cutters, that they formed a free corporation, under the name of "Brother-builders," with especial rights and privileges, all over Germany. Their labors were supported by the power of the Church, the wealth of the merchants and the toil of the vassals, and the masterpieces of Gothic architecture arose under their hands. The grand Cathedrals of Strasburg, Freiburg and Cologne with many others, yet remain as monuments of their genius and skill. But the private dwellings, also, now began to display the wealth and taste of their owners. They were usually built very high, with pointed gables facing the street, and adorned with sculptured designs: frequently the upper stories projected over the lower, forming a shelter for the open shops in the first story. As the cities were walled for defence, the space within the walls was too valuable to be given to wide squares and streets: hence there was usually one open market-place, which also served for all public ceremonies, and the streets were dark and narrow. In spite of the prevailing power of the Roman Church, the Universities now began to exercise some influence. Those of Bologna and Padua were frequented by throngs of students, who attended the schools of law, while the University of Salerno, under the patronage of Manfred, became a distinguished school of medicine. The Arabic university of Cordova, in Spain, also attracted many students from all the Christian lands of Europe. Works on all branches of knowledge were greatly multiplied, so that the copying of them became a new profession. For the first time, there were written forms of law for the instruction of the people. In the northern part of Germany appeared a work called "The Saxon's Looking-Glass," which was soon accepted as a legal authority by the people. But it was too liberal for the priests, and under their influence another work, "The Suabian's Looking-Glass," was written and circulated in Southern Germany. The former book declares that the Emperor has his power from God; the latter that he has it from the Pope. The Saxon is told that no man can justly hold another man as property, and that the people were made vassals through force and wrong; the Suabian is taught that obedience to rulers is his chief duty. [Sidenote: 1260. CLASSES OF THE PEOPLE.]