|Length:||113 km (70 mi)|
|States:||Lower Saxony, Thuringia|
Districts and municipalities
- Lower Saxony
- Hildesheim (district)
- Goslar (district)
- Osterode am Harz (district)
- From Seesen to AS Engelade combined with the B 248
- Between AS Münchehof and Bad Grund combined with the B 242
- In Osterode between Osterode Mitte and Osterode Süd combined with the B 241
- Between Herzberg and Barbis combined with the B 27
- Beuster, near Hildesheim-Marienburg
- Lamme, near Wesseln
- Nette, near Bockenem and Engelade
- Söse, in Osterode
- Sieber, in Herzberg
- Oder, in Barbis – village in borough of Bad Lauterberg
- Steina, in Nüxei – village in borough of Bad Sachsa
- Uffe, near Holbach
The metalled artificial road (Chaussee) between Seesen and Osterode was built between 1785 and 1795 as an extension of the Frankfurt Road and known as the Thuringian Road (Thüringer Straße).
It was established as Reichsstraße 243 between Hildesheim and Nordhausen in 1937.
This federal road was interrupted by the division of Germany and was only opened again from end to end on 18 November 1989 when the border crossing between Nüxei and Mackenrode was installed.