An altarpiece is a work of art set above or behind an altar in a Christian church. Depicting religious subjects such as Christ's death and resurrection, altarpieces proliferated during the late Medieval and Renaissance periods, particularly in Italy and Northern Europe. Altarpieces were often painted on panel, or sculpted in wood and stone, and range in size from small panels to multi-panelled formats known as polyptychs which were hinged so they could be opened and closed.