The opening scene was shot inside the famous Uffizi Gallery in Florence. As of 2014, Dario Argento is the only director who's ever received permission to film inside the museum.
Ennio Morricone's eerie music score for the film follows the same tune played either forward or backward!
Director Dario Argento said he actually experienced Stendhal Syndrome as a child. While touring Athens with his parents, young Dario was climbing the steps of the Parthenon when he was overcome by a trance that caused him to become lost from his parents for hours. The experience was so strong that Argento never forgot it and immediately thought of it when he came across Magherini's book, which would become the basis of the film.
This was reportedly the first feature film made in Italy to use CGI.
Graffiti artists were brought in to cover the underground lair of Alfredo with graffiti. In one night the group created over a hundred square feet of graffiti-covered walls on the location.