Aarau is the capital of the northern Swiss canton of Aargau. The city is also the capital of the district of Aarau. It is German-speaking and predominantly Protestant. Aarau is situated on the Swiss plateau, in the valley of the Aar, on the river's right bank, and at the southern foot of the Jura mountains,and is west of Zurich.The municipality borders directly on the Canton of Solothurn to the west. It is the third-largest city in Aargau after Wettingen and Baden. At the beginning of 2010 Rohr became a suburb of Aarau.