Essen Minster (German: Essener Münster), since 1958 also Essen Cathedral (Essener Dom) is the seat of the Roman Catholic Bishop of Essen, the "Diocese of the Ruhr", founded in 1958. The church, dedicated to Saints Cosmas and Damian and the Blessed Virgin Mary, stands on the Burgplatz in the centre of the city of Essen, Germany. The minster was formerly the collegiate church of Essen Abbey, founded in about 845 by Altfrid, Bishop of Hildesheim, around which the city of Essen grew up. The present building, which was reconstructed after its destruction in World War II, is a Gothic hall church, built after 1275 in light-coloured sandstone. The octagonal westwork and the crypt are survivors of the Ottonian pre-Romanesque building that once stood here. The separate Church of St. Johann Baptist stands at the west end of the minster, connected to the westwork by a short atrium – it was formerly the parish church of the abbey's subjects. To the north of the minster is a cloister that once served the abbey. Essen Minster is noted for its treasury (Domschatz), which among other treasures contains the Golden Madonna, the oldest fully sculptural figure of Mary north of the Alps.