A wall of blue glass has been erected in Berlin as a monument in remembrance of the disabled individuals who were euthanized during the Third Reich’s rule, the Süddeutsche Zeitung reported.

Between 1939 and 1941 “Aktion T4” was introduced to systematically murder over 70,000 mentally ill and disabled patients across hospitals and clinics in Germany. Hitler’s rationale was that the concurrent invasion of Poland, which started the Second World War, would defer attention away from the domestic atrocities he had ordered. “Aktion T4” was officially ended in 1941 after mounting pressure from the public and especially the Church, although individual murders of patients continued.

The victims of “Aktion T4” have been remembered in Berlin since the 1980s. A plaque stands in front of the Berlin Philharmonic Orchestra at Tiergartenstraße 4 where the villa once stood in which the crimes were conceived. Next to the plaque stands a sculpture by Richard Serra: two high, slightly curved steel plates forming a ravine. The sculpture was conceived by Serra to stand in front of the Martin Gropius Bau museum. However, when the city council was offered the artwork, they purchased it anyway and used it as a monument.

This arrangement seemed inadequate and critics have pointed out in recent years that the monument was too ambiguous. A purpose-built monument in the form of a large, gently inclined wall of blue glass has now been constructed by architect Ursula Wilms, artist Nikolaus Koliusis, and landscape architect Heinz W. Hallmann.

According to Wilms the monument expresses “something that should stand out,” the public must recognize that “something enormous stands there.” Willms adds that “We always wanted to both express both the side of the perpetrators and the victims.”