 His first commissions in about 1596 were completed with Giuseppe Valeriano who asked Celio to decorate the Chapel of the Passion in the church of il Gesù in Rome.This work was done after the design of P. Giovanni Battista Fiammeri.He also paints a "Madonna and Bambino", now in Santa Maria del Carmine, a "The Passage of Moses through the Red Sea" (1607) in a vault of the Palazzo Mattei, a "Death of the Giants".