Terragni’s last major project was the design of the Dante Museum and Institute in Rome. The program was approved by Mussolini, but did not build because of war. In this scheme, Terragni sought a constructional interpretation that would be comparable to the three canticas of the Danteum, but also  depict the image of his mind. He thought this was a particularly important task to improve fanatical nationalism under the Italian fascist regime.

With Italy involved in the Second World War, Terragni joined the Italian army. He fought on the front lines of Greece and the Soviet Union. In January 1943, he returned home, died in July, the same year in July after the fall of the fascist regime, he died because cerebrovascular disease.