LONDON.- Altarpiece: An image-bearing structure placed upon or behind an altar in a Christian church. Usually forms the focus of devotion for worshippers and is normally decorated by painters and/or sculptors. Altarpieces can vary considerably in size and in complexity of construction, ranging from simple dossals (a horizontal panel or cloth either fronting or set at the back of an altar) to huge polyptychs (a painting divided into multiple sections or panels). They are decorated with a range of imagery which often reflects the circumstances of their original commission and location. As part of a new series of summer exhibitions drawn from the National Gallery’s permanent collection, ‘Devotion by Design’ focuses on Italian altarpieces ranging from the 13th century to the end of the 15th