sanctuary knocker

sanctuary knocker, in architecture, knocker on the outer door of a Christian church. The sanctuary knocker could be a simple metal ring, which accounts for its other name of sanctuary ring, or it could be highly ornamental, as in the Norman example at Durham cathedral in England, dating from the turn of the 12th century. According to the ecclesiastical law of the Middle Ages, a fugitive had only to touch the sanctuary knocker in order to be immune from arrest.