The next four most popular parties were the SVP (18%), the FDP (14%), the GPS (10.7%), the GLP (9.2%). In the federal election, a total of 114,377 voters were cast, and the voter turnout was 46.2%. Zürich is partnered with two sister cities: Kunming and San Francisco. Zürich is situated at above sea level on the lower (northern) end of Lake Zürich (') about north of the Alps, nestling between the wooded hills on the west and east side. The Old Town stretches on both sides of the Limmat, which flows from the lake, running northwards at first and then gradually turning into a curve to the west. The geographic (and historic) centre of the city is the Lindenhof, a small natural hill on the west bank of the Limmat, about north of where the river issues from Lake Zürich. Today the incorporated city stretches somewhat beyond the natural confines of the hills and includes some districts to the northeast in the Glatt Valley (') and to the north in the Limmat Valley (""). The boundaries of the older city are easy to recognize by the Schanzengraben canal. This artificial watercourse has been used for the construction of the third fortress in the 17th and 18th centuries. The municipality of Zürich has an area of , of which is made up of Lake Zürich. The area includes a section of the northern Swiss Plateau. The banks of the Limmat constitute the densest part of the city. The river is oriented in the southeast–northwest direction, with the flat valley floor having a width of two to . The partially channeled and straightened Limmat does not flow in the central part of the valley, but always along its right (northeastern) side. The Sihl meets with the Limmat at the end of Platzspitz, which borders the Swiss National Museum. The Limmat reaches the lowest point of the municipality in Oberengstringen at above sea level. On its west side, the Limmat valley is flanked by the wooded heights of the Albis chain, which runs along the western border. The Uetliberg is, with above sea level, the highest elevation of the surrounding area. Its summit can be reached easily by the Uetlibergbahn. From the platform of the observation tower on the summit, an impressive panorama of the city, the lake, and the Alps can be seen.