The Walnut Street Theatre is the oldest operating theatre in the world. It is located at 825 Walnut Street in the Washington Square West neighbourhood of Philadelphia, Pennsylvania. The Walnut Street Theatre was built by the Circus of Pepin and Breschard. The first theatrical production at the theatre was, ‘The Rivals in 1812’. The theatre opened in 1809. A few years later, an 80-feet dome was added to the theatre. It became the tallest structure in Philadelphia. In 1837, the Walnut was the first theatre to install gas footlights. In 1855, the Walnut Theatre became the first theatre to install air conditioning.