External Decoration

The external decoration of a cathedral or large church building is often both architectural and pictorial. Decorative architectural devices include columns, pilasters, arcading, cornices, moldings, finials and tracery. The forms taken by these features is one of the clearest indications of the style and date of any particular building. Pictorial elements may include sculpture, painting and mosaic.

Sculpture is the predominant pictorial decorative element in most regions where buildings are of stone construction. In the great medieval churches of France, Spain, England and much of Germany, figurative sculpture is found adorning facades and portals.

Churches of brick, such as those of much of Italy, are often adorned with mosaics, inlays, inset marble friezes and free-standing statues at the roofline. Mosaics were a particular feature of Byzantine architecture and are the main form of adornment of many Orthodox churches, both externally and internally.

The most common theme in the decoration, both external and internal, of any church, is the salvation of humankind by Jesus Christ. The decorative scheme often functions as a Poor Man's Bible, warning the church-goer that, in Biblical terms, the just rewards for his sinful nature is death, and that only through Jesus can forgiveness and redemption be gained. The scheme typically starts outside the church, on the west front, with the portrayal of Christ the Judge above the lintel of the main door. In Romanesque and Gothic buildings, this is usually a sculptural group, and may entail a whole scene of the Last Judgement with details of souls being weighed and rewarded, or dragged down to Hell by demons. In those churches in which painted rather than sculptured decoration prevails, the Last Judgement is often located on the interior of the west end, rather than the interior.

Nave and aisles

The main body of the building, making the longer arm of the cross, where worshippers congregate, is called the nave. The term is from the Latin word for ship. A cathedral is symbolically a ship bearing the people of God through the storms of life. In addition, the high wooden roof of a large church is similarly constructed to the hull of a ship.

The nave is braced on either side by lower aisles, separated from the main space by a row of piers or columns. The aisles facilitate the movement of people, even when the nave is full of worshippers. They also strengthen the structure by buttressing the inner walls that carry the high roof, which in the case of many cathedrals and other large churches, is made of stone. Above the roof of the aisle are the clerestory windows which light the nave.

In some large churches, particularly late Medieval churches, there are two aisles on either side of nave. Other churches have a single aisle and a row of chapels on either side. In some churches, particularly in Germany, the aisles are almost as high as the nave, forming a "hall church". In this case, because there is no clerestory, the aisle windows are often very tall, to admit light to the nave.