Introduction to the Palace Theater: The Royal Theater (Slottsteatern) was built in 1766 and is the only theater in the world that has remained unchanged for more than 200 years. In 1792, King Gustav III of Sweden was assassinated during a ball held at the theater, and the theater was closed for a time. In 1922, the renovated theater retained the original layout of various props, devices, equipment and stages used more than a hundred years ago, and it is still used as a performance venue for classical repertoire.