Observation skills, logical reasoning, knowledge. Hard not to recognize the essential role played by such qualities, their detection activity, even in architectural survey, especially if the goal is to resolve puzzles rather than highlight opacity. The three presented “cases”, in fact, move from many a circumstantial evidence: a ruined window in the garden of Pieve del Vescovo, a negative critique about the colonnade of St. Peter’s Square, a pale draft in the church of the Madonna del Prato. Reaching surprising results, which add unthought meaning to three major players in the history of post-Renaissance, such as the picturesque vein of Galeazzo Alessi, the syntactic licentiousness of Gian Lorenzo Bernini and Francesco Borromini’s critical revisionism.