the film's first sequence, shot in an alleyway near Dinocittà, he states that Bava opens the film with "a parade of illusions", most notably the establishing shot of a bank, which utilizes a travelling matte that adds multiple floors to a single-floor structure while duplicating the structure to the opposite side of the screen; to visually lend scale to the matte, toy figurines are used to represent soldiers standing guard on both sides of the structure, while a toy tank is visible in the foreground as a motorcade of police officers on motorcycles ride through the structure's gate in the lower section of the composition — the only part of the set that was actually built. He describes this as "a staggering pre-digital effect, and it's only there not to be noticed". Aside from this example and Diabolik's car hangar, other instances of Bava's in-camera matte work in the film include the exteriors of Saint Just Castle — which were filmed on the beaches of Tor Caldara, where he employed similar effects for Erik the Conqueror, The Whip and the Body, Knives of the Avenger, Five Dolls for an August Moon and Roy Colt & Winchester Jack — Valmont's runway (for which only one wing and a portion of a plane's hull were painted) and the cabin in which Eva is held hostage; although an establishing shot of Valmont's plane flying towards the runway was shot with a specially-prepared matte, the sequence was ultimately cut from the finished film. For the sequence in which Diabolik scales the castle wall, a convex section of material was built at a 35 degree angle, allowing Law to "climb" the wall without needing to be doubled by the film's stunt coordinator, Gofreddo "Freddy" Unger (who instead doubled for him during Diabolik's dive into a harbor in the pre-title sequence); the scene was shot with wide-angle lenses to lend a sense of depth and height. The underwater sequences of Diabolik and Eva's recovery of the gold were shot by a second unit supervised by Francisco Baldini; these are interspersed with close-ups of Law and Mell's faces that were filmed "dry" in front of an aquarium. Lucas is more critical of Bava's uncharacteristic use of optical overlays and chroma key effects, deeming them to be aspects of the production that were likely forced upon him by De Laurentiis: in the scene in which Diabolik and Valmont