Bern lies on the Swiss plateau in the Canton of Bern, slightly west of the centre of Switzerland and 20 km (12 mi) north of the Bernese Alps. The countryside around Bern was formed by glaciers during the most recent Ice Age. The two mountains closest to Bern are Gurten and Bantiger with a height of 947 m (3,107 ft). The site of the old observatory in Bern is the point of origin of the CH1903
The city was originally built on a hilly peninsula surrounded by the River Aare, but outgrew natural boundaries by the 19th century. A number of bridges have been built to allow the city to expand beyond the Aare.
Bern is built on very uneven ground. There is an elevation difference of several metres between the inner city districts on the Aare (Matte, Marzili) and the higher ones (Kirchenfeld, Länggasse).