Altar of St Jerome The mosaic is a copy of a painting by Domenichino (1581-1641), which now hangs in the Vatican's Pinacoteca. It depicts The Last communion of St Jerome. Under the altar lies the body of Saint John XXIII (r. 1958-63), which was placed here following his beatification on September 3rd, 2000. He was canonised on April 27th, 2014.