After a trip to the United States in 1922, he designed steamship décor for the Norddeutscher Lloyd shipping company before World War I, and the fittings for transatlantic liners in a style that combined Spartan traditionalism with elements of modernity.

[4] Along with other architects like Ludwig Ruff, Troost planned and built State and municipal edifices throughout the country, including new administrative offices, social buildings for workers and bridges across the main highways.

One of the many structures he planned before his death was the Haus der Deutschen Kunst ("House of German Art") in Munich,[5] modeled on Schinkel's Altes Museum in Berlin.

It was a good example of the imitation of classical forms in monumental public buildings during the Third Reich, though subsequently Hitler moved away from the more restrained style of Troost, reverting to the more elaborate imperial grandeur that he had admired in the 19th century Vienna Ring Road (Ringstraße) boulevard of his youth.

According to Albert Speer, who later became Hitler's favorite architect, the Führer would impatiently greet Troost with the words: "I can't wait, Herr Professor.

The architect's death on 21 January 1934, after a severe illness, was a painful blow, but Hitler remained close to his widow Gerdy Troost, whose architectural taste frequently coincided with his own, which made her (in Speer's words) "a kind of arbiter of art in Munich".