3D modeling of the historic Market Square of the medieval town of Calw. Calw, a medieval town in the northern part of the Black Forrest, has a great history. In the 15th, 16th and 17th century this town was a commercial center of wood dissemination and processing, cloth production and salt trade. At this point in time it was much more important as a centre of commerce than the city of Stuttgart. Close to Calw are the ruins of Hirsau Abbey, once known as the “Hirschau Abbey (most probably because of the Swabian dialect or may be because of many deers around) was one of the most prominent Benedictine abbeys of Germany. Founded around 830 AD by Count Erl afried of Calw the Aurelius Monastery served as an abbey for about 200 years. Later on – around 980-1020) the monastery St. Peter and Paul (very close to Aurelius) was built and served as the center of the Benedictine movement until it was destroyed by French soldiers in 1692. This disastrous moment had also a huge impact on Calw, as most of its medieval houses have been burned and destroyed as well. By the way, the famous William of Hirsau, abbot from 1069 to 1091, introduced the Astrolab for measuring latitude positions. Therefore, the Hirsau Abbey served already more than one millennium ago for geodetic purposes, a fact not well-known to the geodetic community. In the 18th and 19th century cloth processing in Calw claimed again a new peak and provided good income and business for a renaissance of the town.