The jewel of Ely's Crown and acknowledged as one of the wonders of the Medieval world.
Disaster struck on 13 February 1322, when the Norman central tower collapsed. The noise was so great that the monks thought there had been an earth quake. Alan of Walsingham, the monk responsible for the building, was deeply shocked. One of his fellow monks wrote: 'He was devastated, grieving vehemently and overcome with sorrow... that he knew not which way to turn himself or what to do for the reparation of such a ruin.'
As rebuilding commenced, firmer foundations were found further out from the original pillars, and from this evolved the idea of building an octagon surmounted by a lantern. Its width of 74 feet (23m) was too great to support a stone vault, and so it was built in wood and covered in lead.
A masterpiece of medieval engineering, it took 18 years to build. The internal height is 142 feet (43m), and its total weight is 400 tons. In the centre, John of Burwell (a village south-east of Ely), carved the beautiful Christ in Majesty. Thousands come to Ely to climb the tower and the internal wooden structure which has baffled architects for centuries.