Stellio Lorenzi was born in Paris to an Italian father from Sanremo. He spent his childhood and adolescence in Cannes then moved to the capital. After three years of graduate studies in mathematics, he turned to architectural. The entrance exam to the École Polytechnique was forbidden to him, because the laws of the Vichy regime refused access to the sons of foreigners. In 1944, he was assistant director to Jacques Becker on Paris Frills. He continued this career until 1951 with directors such as Jacques de Baroncelli, Marc Maurette, Louis Daquinor and Gilles Grangier.