Bern, the capital city of Switzerland, is built around a crook in the Aare River. It traces its origins back to the 12th century, with medieval architecture preserved in the Altstadt (Old Town). The Swiss Parliament and diplomats meet in the Neo-Renaissance Bundeshaus (Federal Palace). St. Lambertus Church and Castle Tower both date to the 13th century. With a population of 141,098 (March 2016), Bern is the fourth most populous city in Switzerland. No archaeological evidence that indicates a settlement on the site of today′s city centre prior to the 12th century has been found so far. 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 climate produces cold snowy winters and warm wet summers.