Hennef (Sieg)
| Hennef  | |
|---|---|
| Aerial view of Hennef, May 2008 | |
| Location of Hennef  within Rhein-Sieg-Kreis   district | |
| Coordinates: 50°47′N 7°17′E / 50.783°N 7.283°E | |
| Country | Germany | 
| State | North Rhine-Westphalia | 
| Admin. region | Köln | 
| District | Rhein-Sieg-Kreis | 
| Government | |
| • Mayor (2020–25) | Mario Dahm (SPD) | 
| Area | |
|  • Total | 105.89 km2 (40.88 sq mi) | 
| Elevation | 68 m (223 ft) | 
| Population  (2023-12-31) | |
|  • Total | 48,295 | 
| • Density | 460/km2 (1,200/sq mi) | 
| Time zone | UTC+01:00 (CET) | 
| • Summer (DST) | UTC+02:00 (CEST) | 
| Postal codes | 53773 | 
| Dialling codes | 02242/02248 | 
| Vehicle registration | SU | 
| Website | www.hennef.de | 
Hennef (Sieg) (German pronunciation: [ˈhɛnɛf] ⓘ) is a town in the Rhein-Sieg district of North Rhine-Westphalia, Germany. It is situated on the river Sieg, approx. 7 kilometres (4 miles) south-east of Siegburg and 15 km (9 mi) east of Bonn. Hennef is the fourth-biggest town in the Rhein-Sieg-Kreis (i.e. district). 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.