This monument was erected in 1950 – the first symbol of remembrance in Hartheim – by the Amicale de Mauthausen, in particular for the French victims from the Mauthausen-Gusen camp system. It is situated next to the castle garden on the northern side of the castle.
In 2003 the Alkoven local authority erected a monument to Ignaz Schuhmann and Leopold Hilgarth, two local victims of the resistance against the National Socialist regime. The monument was placed near the entrance to the castle grounds, not far from the Schuhmann family farmhouse. It was designed by Herbert Friedl.
In 2001, on the initiative of the Hartheim Castle Society, a memorial stone was erected on the bank of the Danube between Brandstatt and Wilhering, near the village of Gstocket (Alkoven district), at the place where the ashes of the murder victims were poured into the river. The inscription on the massive Danube stone comes from the Upper Austrian writer Franz Rieger: “The water erased the traces that memory preserves.” The stone stands at kilometre 2,148.5 of the river, Wendeplatz. The site can be reached via the access road to the Ottensheim/Wilhering Danube power station. From there it is around 1.75 km upstream along the towpath (pedestrian and cycle path).