Altarpieces originate in the Christian tradition of placing a decorated panel on or next to an altar, the table-shaped structure that historically serves as the central focus of a house of worship. Likely emerging between the 9th and 11th centuries to identify the saint or figure associated with the altar, the earliest examples were simple paintings on rectangular wooden panels, usually depicting Jesus or the Virgin Mary. Over time, altarpieces became larger and more elaborate; in the 1200s, Cimabue adopted a large-scale, gabled format with gold ground. By the 1500s the format flourished, resulting in some of the most iconic works of Western Christian art, from the monumental scale and complex iconography of the Ghent Altarpiece to Matthias Grünewald’s winged Isenheim Altarpiece. Italian Renaissance sculptors like Donatello and Michelangelo introduced free-standing sculpture of dramatic proportions alongside the altar (like the latter’s Pietà, 1497-1500), and the use of stone in the construction of ornate sculpture and relief continued through the Baroque.