After a brief stay in Naples Mariano Rossi moved to Rome in 1750. His paintings document his adherence to the traditional neo-baroque of Rome and Naples. Canvases by the artist adorn countless churches in Rome: there are eleven of them in the Church of San Giacomo alla Lungara alone. In 1767 he returned to Sciacca to paint works for the various churches of the city, including: The Assumption of the Virgin Mary in the Church of Giummare, The Virgin comforting souls for the Church of Purgatory. His career was marked by prestigious assignments: in Turin he painted the frescos of the second chamber of archives in the royal palace (1770-71), in Rome, the frescos of the entrance hall at the Villa Borghese (1776-79) and in Caserta, in the Royal Palace, the fresco depicting the Marriage of Alexander the Great and Roxane (1787) in the Alexander Room.