Slottsteater was completed in 1766 on the instructions of Queen Lovisa Ulrika. Remarkably untouched from the time of Gustav III’s death (1792) until 1922, it’s now the oldest theatre in the world still in its original state; performances are held here in summer using 18th-century machinery, including ropes, pulleys, wagons and wind machines. Scenes can be changed in less than seven seconds! Illusion was the order of the day here, and accordingly the theatre makes use of fake marble, fake curtains and papier-mâché viewing boxes. Even the stage was designed to create illusions regarding size. The fascinating guided tour takes you into other rooms in the building, where highlights include hand-painted 18th-century wallpaper and an Italianate room (salon de déjeuner) with fake three-dimensional wall effects and a ceiling that looks like the sky.