Among the other works, he designed mausoleums for Cardinal Inico Caracciolo in Aversa, Cardinal Giuseppe Renato Imperiali in the church of Sant'Agostino in Rome, for cardinal Carafa in Sant'Andrea delle Fratte (1759), and for princess Maria Flaminia Chigi-Odescalchi (1771) in the church of Santa Maria del Popolo.
Posi helped with the ephemeral obsequies held in Santi Apostoli (a church near their residence) in Rome, after the death of James Stuart, the pretender to the crown of England, as well as supervising firework displays for the Colonna.
In 1767, Lorenzo Colonna commissioned Posi to design the ephemeral celebratory machine de artifizio with fireworks on the occasion of the provision of a Chinea, or richly caparisoned mule (symbol and veritable tribute) to Pope Clement XIII.
Nominated as architect to St Peter's Basilica and Knight of the Golden Spur, Posi helped design the Jesuit church in Sinigaglia, and the place of Abbot Farsetti in Santa Maria di Sala, in the Veneto.
He helped rebuild the Palazzo Colonna and rebuilt the church of Santa Caterina dei Senesi.