The opening in a "picture frame" stage. Came into use in Restoration theatre, replacing the thrust stage of Elizabethan theatre and was a standard feature of stages from the 17th Century until open or thrust stages, as well as theatres in the round came into extensive use again in the 20th Century. The proscenium stage was much influenced by the design of theatre houses designed Italy from the 16th Century forward. The proscenium helped to hide the machinery and equipment used to change settings in a production.