This magnificent Gothic structure was constructed between 1613 and 1621. It holds the royal family vault and the huge sarcophagus of Count of Luxembourg John I of Bohemia ("John the Blind"; 1296-1346), in addition to a remarkable treasury (which can only be viewed on request, so ask the sacristan, whose office is on the right as you enter). The cathedral is the scene of the Octave of Our Lady of Luxembourg, an annual ceremony on the fifth Sunday following Easter, when thousands of pilgrims arrive to pray for protection to the miraculous statue of the Holy Virgin. They then form a procession to carry the statue from the cathedral through the streets to an altar covered with flowers on av. de la Porte Neuve, north of place d'Armes.