Pietro Belluschi was born in Ancona, Italy, in 1899. He grew up in Italy and served in the Italian armed forces during World War I when Italy was allied with Great Britain, France, and later the United States. Serving in the army he fought against the Austrians at the battles of Caporetto and Vittorio Veneto. After the war, Belluschi studied at the University of Rome, earning a degree in civil engineering in 1922.