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.