The Heyligenstaedt mechanical engineering company was founded in 1876 by Ludwig (Louis) Heyligenstaedt and the businessman Alexander Sartorius. The company initially produced drilling machines, lathes and planing machines, among other things, on Riegelpfad. The factory was gradually relocated to Aulweg from 1886, initially with the construction of an iron foundry, and in 1895 the machine factory was built. Heyligenstaedt was able to expand as a machine tool manufacturer, both domestically and internationally. In 1896 the company employed 300 workers, and by 1907 it had already reached 500. Despite a crisis and the company being taken over by Rinn & Cloos in 1932, the company was able to recover economically after the Second World War thanks to the rapid growth of automation in car production.
The two two-storey buildings of the mechanical engineering company, the administration building and the factory building, are characterized by the salmon-colored clinker brick. The slated mansard roof is a striking feature of the front administrative building. The industrial building, on the other hand, stands out with its three-part, symmetrical façade. The buildings were badly damaged in the Second World War. Nevertheless, despite individual modernizations, they are well preserved. They are therefore listed as historical monuments due to their urban and artistic qualities and their economic and historical significance.