The massive form of this altar is typical of the 12th century.  It was designed to cover the bodies of the patron saints of the church.  Such venerable monuments were jealously guarded over the centuries. Pilgrims were drawn to the antiquity of the monument, and the splendor of the gem encrusted shrine. (Viollet-le-Duc, Architecture, 2:25: Saint-Denis 12th-century altar and reliquary of the bodies of the founding saints, Denis and his companions, Rusticus and Eleutherius) back to "worship"