The ruins of Old Falkenstein are located in the eastern Harz region of Mansfeld Land between Mägdesprung (north of Harzgerode) and Meisdorf (southwest of Falkenstein/Harz) on a rocky ridge (335.6 m above sea level (NN)[1]) above the valley of the River Selke.

In the forested landscape of the Harz/Saxony-Anhalt Nature Park, it lies within the nature reserve of Selketal ("Selke Valley") about 1.25 kilometres (0.78 mi) northwest of the Köhlerhütte,[2] which itself is northwest of Pansfelde near Kreisstraße 1344.

After the Battle of Welfesholz on 11 February 1115 the castle was slighted under the direction of the Saxon duke, Lothair of Süpplingenburg and was never rebuilt.

[5] Today, elements of the circular moat (Ringgraben) and advanced rampart (Vorwall) as well as remnants of the northern ring wall (Ringmauer) are still visible.

A cross recalls the fatal accident here on 11 July 2003 of local history researcher and area monument curator, Hans Reißmann.