The route known as the "Royal Stairway from Heaven to Earth" offers a chance to appreciate the structural choices made by the architect, Luigi Vanvitelli. From the upper hallway, the upper level can be accessed, right up to the attic walkway. This route offers the chance to observe the counter-vault, once used to accommodate musicians whose job was to play as guests arrived at the court, and to enjoy a close-up of the fresco by Girolamo Starace (1730-1794), depicting the Palace of Apollo surrounded by four medallions showing the Seasons.