🇩🇪 Hennef (Sieg) is a town in the Rhein-Sieg district of North Rhine-Westphalia, Germany. It is situated on the river Sieg, approx. 7 km south-east of Siegburg and 15 km east of Bonn. Hennef is the fourth-biggest town in the Rhein-Sieg-Kreis. It is the site of the 15th century castle, Schloss Allner, next to the Allner See. Within Hennef is the town of Stadt Blankenberg, with the castle of Blankenberg. Hennef is also known as the "City of 100 villages".
Hennef has a population of over 46,114 people. Hennef also forms part of the wider Rhein-Sieg district which has a population of over 600,375 people. Hennef is situated 15 km east of Bonn.