Otranto Cathedral, Ossuary Chapel
In August 1480, clergy and survivors of the Ottoman siege of Otranto took refuge in the cathedral – the Ottoman force eventually broke in and killed those inside, turning the church into a stable or a mosque and destroying its 13th-century frescoes. After Otranto was retaken in 1481 by a force under Alfonso V of Aragon it was turned back into a church and heavily rebuilt to house the relics of the Martyrs of Otranto, who had been executed after the 1480 siege. The reconstruction included the rose window on the gabled west front, with 16 rays of fine Gothic tracery converging at the centre according to the canons of Gothic architecture. In the south aisle is the Chapel of the Martyrs, built by order of Ferdinand I of Naples and rebuilt at public expense in 1711 – this houses the relics of the martyrs in seven large coffins. Behind the chapel's altar is the 'stone of martyrdom', traditionally held to be that used to behead the martyrs.