The venue is operated by the Walnut Street Theatre Company, a non-profit organization, and has three stages: the Mainstage, for the company's primary and larger productions, the Independence Studio on 3, a studio located on the building's third floor for smaller productions, and the Studio 5 on the fifth floor, which is rented out for independent productions. In May 2019, the Walnut Street Theatre announced a major expansion, to begin in 2020.
The Walnut Street Theatre was built by the Circus of Pepin and Breschard, which toured the United States from 1807 until 1815. Pepin and Breschard constructed numerous venues in cities along the East Coast of the United States, which often featured, along with performances of their circus, classical plays as well as horse dramas.
The theatre was founded in 1809, going by the name of The New Circus. In 1811, the two partners commissioned architect William Strickland to design and construct a stage and orchestra pit for theatrical performances and the theatre's name was changed to The Olympic. The official website says that the name The Walnut Street Theatre was first used there in 1820, though the name was changed back to The Olympic in 1822 and to The Walnut again in 1828. A travel guidebook from 1849 indicates that in the mid-19th century, this building was called The American Theatre.
The Walnut was the first theatre to install gas footlights in 1837. In 1855, it was also the first theatre to feature air conditioning. The theatre switched to electric chandeliers and footlights in 1892. The theatre has undergone many renovations since its opening.
The first theatrical production at the theatre was The Rivals in 1812 (President Thomas Jefferson and the Marquis de Lafayette were in attendance). Edwin Booth and John Sleeper Clarke purchased the theatre in 1865, and then the theatre became part of The Shubert Organization in 1941.
According to wikipedia