Ruskin 's reference is to the cathedral of Notre Dame at Chartres in north west France which was rebuilt after a fire had destroyed Bishop Fulbert's Romanesque predecessor in 1194. Regarded as the key building in the development of High Gothic, it saw the reduction of the internal elevation to three storeys, comprising a high nave arcade, a low triforium and clerestorey windows equalling in height the nave arcade. The structure was stabilised externally by three-arched flying buttresses. The nave piers have slender attached shafts which rise to the point from which the vaults spring where they link with the vaulting ribs. Chartres is iconologically rich, both in the sculpture of its three porches which show the development of medieval sculpture from that of the royal portal (1134-1140) through the north porch (1197-1206) and the south porch (1206), and in the largely intact thirteenth-century stained glass of its one hundred and sixty windows. Nine towers were proposed but only the western two were built, the north west of circa 1140 being capped by a flamboyant spire in 1507 following the destruction of the earlier spire by lightning. With its earlier and intact counterpart, the south west tower, it is possible to see the evolution of the Gothic style from its earlier to its later phases. In Modern Painters Ruskin compares the representational techniques of stone sculpture at Lucca with that of the stained glass of Chartres. Ruskin's visits to Chartres included those made in 1840, 1842, 1844, 1854, 1866 and 1880. Ruskin describes the Cathedral of Chartres as the 'true centre of Gothic power' in France, its counterpart in England being the Cathedral of Wells and that in Italy the Duomo of Florence, all being notable for their 'noble figure sculpture' ( Works, 16.311).