The Hotel Excelsior opened on January 18, 1906. It was constructed by the Actiengesellschaft für Hotelunternehmungen, based in Lucerne, Switzerland. They sold the hotel in 1920 to CIGA, the Compagnia Italiana Grandi Alberghi, or Italian Grand Hotels Company, an Italian luxury chain. In 1944, the hotel became the temporary headquarters of General Mark Clark after the US Army entered Rome.