With the exception of the years 1640-1642, when he was in France, he remained in Rome for the rest of his life. Maffeo Cardinal Barberini, later Pope Urban VIII, became his patron, and Barberini's secretary, Cassiano dal Pozzo, was Poussin's closest friend.
He became famous for his classical landscapes and historical paintings, which were inspired by antique cameos, Titian and Raphael and other sources.
He married his landlord's daughter, Anne Marie Dughet. Her brother, Gaspard Dughet, became a well-known landscape painter, often referred to as 'Il Poussin'.
He died in Rome in 1665, and is buried in San Lorenzo in Lucina.