Drottningholm Palace Theater (Drottningholms Slottsteater) was built in 1766 at the request of Queen Lovisa Ulrika. The theater’s golden age began in 1777 but did not last long. It flourished thanks to  King Gustaf III who together with actors like Monvel, the composers Naumann and Kraus, and the ballet master Gallodier used Drottningholm to inject new life into Swedish theatre and opera. The repertoire included Gluck’s latest works, opéras comiques, French classical dramas and ballets. After the King’s death in 1792 the theater was closed.

For more than a hundred years the place had been forgotten. When  historian Agne Beijer walked through the door in 1921 he discovered a sleeping beauty, practically untouched since the end of the 18th century. Not only was the interior intact, but most importantly the stage machinery had survived and works even today - a rare example of working stage effects from those times. One of the stage machines that is still intact and in use in the theater is the chariot-and-pole system, which helps to change scenes quickly by sliding the wings with wheels (“chariots”) on tracks in the floor, controlled by a capstan under the stage (“pole”).  There are also special effects machines, including a wave machine to simulate a rough sea, thunder machine to create storm sound effects, and a flying chair which is often used for "deus ex machina" effects. 

The necessary repair works were done, electric lights installed and old ropes replaced. Most of the interior remained unchanged in its original design. In 1922 the theater opened its doors again, and since then every summer it offers new productions of 17th and 18th century operas. 

Drottningholm Palace Theater was featured in Bergman's film The Magic Flute. Originally, Bergman wanted to film inside the theater. However, "the scenery was considered too fragile to accommodate a film crew. So the stage – complete with wings, curtains, and wind machines – was painstakingly copied and erected in the studios of the Swedish Film Institute". Only the introductory exterior shots of the theater in the film are real.

Since 1991, the theater has been on UNESCO list of World Heritage Sites. 

Sources: https://dtm.se, Wikipedia,  Peter Cowie "The Magic Flute". Notes on the film