An altarpiece is an work of art in painting, sculpture or relief representing a religious subject made for placing at the back of or behind the altar of a Christian church. Though most commonly used for a single work of art such as a painting or sculpture, or a set of them, the word can also be used of the whole ensemble behind an altar, otherwise known as a reredos, including what is often an elaborate frame for the central image or images. Altarpieces were one of the most important products of Christian art especially from the late Middle Ages to the era of Baroque painting.
The Ghent Altarpiece (1432) by Hubert and Jan van Eyck, with its wings open. Considered one of the masterpieces of Early Netherlandish painting, a complex polyptych panel winged altarpiece, which lost its elaborate framework in the Reformation.
Ghent Altarpiece (1432), as above, closed view with the wings folded in.
Vigoroso da Siena's altarpiece from 1291, an example of an early painted panel altarpiece, with the individual parts framed by gables and sculptured elements
Rothenburg: The Altarpiece of the Holy Blood, by Tilman Riemenschneider (1501–1505). An example of an altarpiece with a central, sculpted section and relief wings.
Relief is a sculptural method in which the sculpted pieces remain attached to a solid background of the same material. The term relief is from the Latin verb relevare, to raise. To create a sculpture in relief is to give the impression that the sculpted material has been raised above the background plane. When a relief is carved into a flat surface of stone or wood, the field is actually lowered, leaving the unsculpted areas seeming higher. The approach requires a lot of chiselling away of the background, which takes a long time. On the other hand, a relief saves forming the rear of a subject, and is less fragile and more securely fixed than a sculpture in the round, especially one of a standing figure where the ankles are a potential weak point, particularly in stone. In other materials such as metal, clay, plaster stucco, ceramics or papier-mâché the form can be simply added to or raised up from the background. Monumental bronze reliefs are made by casting.
Side view of Lorenzo Ghiberti's cast gilt-bronze Gates of Paradise at the Florence Baptistery in Florence, Italy, combining high-relief main figures with backgrounds mostly in low relief.
A common mixture of high and low relief, in the Roman Ara Pacis, placed to be seen from below. Low relief background
A low-relief dating to c. 2000 BC, from the kingdom of Simurrum, modern Iraq
"Blocked-out" unfinished low relief of Ahkenaten and Nefertiti; unfinished Greek and Persian high-reliefs show the same method of beginning a work.