The Lady chapel, built to honour the Virgin Mary, is the largest of its kind in any British Cathedral. The stone vault spans 13.8m (46ft). The foundations were dug in 1321 and the Chapel was completed in 1349. It originally had richly carved and painted walls with fine medieval glass and many statues. These were all destroyed or damaged in the Reformation of 1539. The Lady Chapel then became a parish church known as Holy Trinity Church. In 19388 it became a Lady Chapel again. The accoustics in the chapel are so good with a 7 second echo that choirs from all over the world visit to sing in its unique atmosphere. In recent years the Lady Chapel has undergone a great deal of restoration including an archeological survey, raising the floor, laying a sub floor and installation of heating and the laying of a new Purbeck marble floor. The Cathedral was originally founded as a monastery in 673 by St Etheldreda, a Saxon Princess from East Anglia. The site of her shrine is in front of the High Altar. The Danes destroyed the monastery in 870 and it was refounded in 970 as a Benedictine community. The present building was started in the 1080s by Abbot Simeon and it became a Cathedral, the seat of the Bishop, in 1109. King Henry VIII closed the monastery in 1539 during the dissolution of the monasteries in the Reformation but it has remained a Cathedral to the present day. Cathedral Church of the Holy and Undivided Trinity of Ely. Diocese of Ely, East Anglia. Known as the Ship of the Fens.