Cathedral diagram

In Western ecclesiastical architecture, a cathedral diagram is a floor plan showing the sections of walls and piers, giving an idea of the profiles of their columns and ribbing. Light double lines in perimeter walls indicate glazed windows. Dashed lines show the ribs of the vaulting overhead. By convention, ecclesiastical floorplans are shown map-fashion, with north to the top and the liturgical east end to the right.

Many abbey churches have floorplans that are comparable to cathedrals, though sometimes with more emphasis on the sanctuary and choir spaces that are reserved for the religious community. Smaller churches are similarly planned, with simplifications.

Cathedral floorplans are designed to provide for the liturgical rites of the church. Before the legalization of Christianity by Emperor Constantine, Christians worshiped in private homes or in secretive locations. Once legally able to publicly worship, the local churches adapted the available Roman designs to their needs. Unlike the Roman and Greek religions, where priests performed rituals without public participation, Christian worship involved the believers. Thus, the limited spaces used in pagan temples were not suitable to Christian worship. Roman civic buildings were designed for the participation of the citizens of the city, and thus the Roman Basilica was adopted for Christian purposes. This included an entry on one end of a long narrow, covered space with a raised dais at the other end. Upon the dais, public officials would hear legal cases, or expound on some matter of public interest. Christians adopted the long hall of the basilica for the public liturgy of the Mass. With the legalization of Christianity in 311 A.D., the church adopted a political structure that mimicked the Roman world. The designation of Bishops began at that time and the designation of his cathedra or Cathedral.

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