Begun in 1173 AD, the tower has been an architectural problem almost from its beginning. Owing to soft ground and a shallow foundation, the tower began to lean as early as the time the third floor was completed. This despite the over 13 foot-thick walls at the base. But engineers at the time had few resources to call on. There was no ground penetrating radar, geological science, lasers or huge cranes to right the work.
Begun in 1063, over a hundred years prior to the tower, the cathedral is the very prototype of late Romanesque architecture in this area of the world. With a floor plan in the standard shape of a cross, it is 100m (328 feet) long by 35m (115 feet) wide. Though not enormously tall by contemporary standards its 34m (112 feet) height would have been extremely impressive to citizens of its day.