The IG Farben Building, designed in 1928 by Hans Poelzig in stripped-back modernist style, is one of the most architecturally significant buildings in Frankfurt — a vast curving sandstone slab nearly 250 metres long that was for a time the largest office complex in Europe. It was built as the headquarters of the IG Farben chemical cartel, which during the Third Reich became a major producer of Zyklon B and ran the Buna synthetic rubber plant at Auschwitz; the company was broken up after the war and its directors put on trial at Nuremberg.
From 1945 to 1995 the building served as the US Army's European headquarters — the so-called "Pentagon of the West". When the Americans left, the building was transferred to Goethe University, which restored it carefully and now uses it as the centrepiece of its Westend campus. The Paternoster lift — a continuous open-cabin elevator that locals still ride for the novelty — is one of the few in Germany still in regular operation. Visitors can walk freely through the lobby and gardens during university hours.