The Rhein-Sieg-Kreis is a Kreis (district) in the south of North Rhine-Westphalia, Germany. Neighboring districts are Rheinisch-Bergischer Kreis, Oberbergischer Kreis, Altenkirchen, Neuwied, Ahrweiler, Euskirchen, Rhein-Erft-Kreis, the urban district of Cologne. The federal city of Bonn is nearly completely surrounded by the district.

The Oberbergischer Kreis is a Kreis (district) in the state of North Rhine-Westphalia, Germany. Neighboring districts are Ennepe-Ruhr, Märkischer Kreis, Olpe, Altenkirchen, Rhein-Sieg, Rheinisch-Bergischer Kreis, and the urban districts Remscheid and Wuppertal.