Cathédrale Saint-Pierre de Beauvais is in some respects the most daring achievement of Gothic architecture, and consists only of a transept and choir with apse and seven apse-chapels. The small Romanesque church of the 10th century known as the Basse Oeuvre occupies the site destined for the nave. The vaulting in the interior of the choir reaches 48 metres in height, far surpassing the concurrently constructed Cathedral of Notre-Dame in Amiens (42 metres). The church, begun in 1247, was never finished. Some of the vaulting of the choir collapsed in 1284 and in 1573 the fall of the central tower stopped work again.