The best time of the day to visit the observation deck in the Orange Garden (Giardino degli Aranci) in Rome is during the late afternoon, just before sunset. This timing lets you witness the captivating golden light illuminating the city's iconic landmarks, such as St. Peter's Basilica, the Tiber River, and the Trastevere Neighborhood. As the sun sets, you can enjoy the breathtaking panorama of Rome bathed in a warm, enchanting glow, creating an unforgettable experience.