to date from the 4th or 5th century. Some time around 1030, Count Egino started to build a castle on top of the Achalm, one of the largest mountains in Reutlingen district (about 706 m). One of the towers of this castle was rebuilt in the 19th century and is open to visitors. The name Reutlingen was first mentioned in writing in the so-called Bempflingen Treaty which is dated approximately 1089-90.

Reutlingen's earliest documented mention dates back to 1089 in the Bempflingen Treaty, which was an inheritance agreement between Zwiefalten