Art auctions deal with the public sale of artworks, usually by a professional auction house such as Christie’s or Sotheby’s. An auction house may sometimes refer to the facility that an auction is taking place in, but most commonly refers to the company running the auction. While auctions technically are public events, they are usually restricted to exclusive audiences within the art world. Auctions take place in many different facilities, as well as in open-air public spaces. Enclosed showroom auction houses began in the 17th century. The oldest auction house is the Stockholms Auktionsverk in Stockholm, Sweden. It was founded in 1674.