The Dufourspitze of Monte Rosa is the most elevated point of Valais and Switzerland, although it is not the most prominent of the country, that distinction belonging to the Finsteraarhorn, nor the most isolated, that distinction belonging to Piz Bernina. The Swiss national map gives an elevation of for the summit, which is 4,441 metres above Lake Maggiore, Switzerland's lowest point. The height difference between the summit and the plains of northern Italy, from where Monte Rosa is well visible, reaches over . Monte Rosa has a topographic prominence of , the Great St Bernard Pass being the lowest col between it and the culminating point of the Alps. A 2000 survey, involving universities and the offices of cartography of Italy and Switzerland and part of the TOWER project (Top of the World Elevations Remeasurement), was made in order to record a more precise elevation for Monte Rosa. The result was from the Italian side and from the Swiss side, with a margin of error of 0.1 m. Monte Rosa succeeded the Finsteraarhorn as the highest summit of Switzerland in 1815, when Valais joined the Swiss Confederation.