Altars could be located in one of the radiating chapels or abutting the walls of the church.  Such a proliferation of altars allowed Masses to be said by the many clergy as well facilitating pilgrims' visits to sites of holy relics enshrined in or above the altars.  Here a reliquary is displayed under an architectural canopy and a vigil light hangs before it, proclaiming the sanctity of the site. (Viollet-le-Duc, Architecture, 2:42: altar with reliquary of the body of St. Hilaire, Saint-Denis, mid 13th century) back to "worship"