Original: Since 19 March 1803, Rheinfelden has been the capital of a district of the same name, in the canton of Aargau.
Simplified: Rheinfelden is a municipality of the canton of Aargau in Switzerland, seat of the district of Rheinfelden. Since 19 March 1803, Rheinfelden has been the capital of the district of the same name, in the canton of Aargau.