The hall was built in 1855–57 and is the oldest opera house in the United States that is still used for its original purpose. Known as the "Grand Old Lady of Locust Street," the venue is the home of the Pennsylvania Ballet and Opera Philadelphia. It was also home to the Philadelphia Orchestra from its inception in 1900 until 2001, when the orchestra moved to the new Kimmel Center for the Performing Arts. The Philadelphia Orchestra still retains ownership of the Academy.
The theatre had its first opera production, and what was billed as its formal opening, a month later on February 25, 1857, with a performance by the Max Maretzek Italian Opera Company of Verdi's Il trovatore starring Marietta Gazzaniga as Leonora, Alessandro Amodio as Count di Luna, Zoë Aldini as Azucena, Pasquale Brignoli as Manrico, and Max Maretzek conducting.
The auditorium is graced by a large crystal chandelier, which measures 16 ft (4.9 m) in diameter, and weighs 5,000 lb (2,300 kg). When installed, the chandelier contained 240 gas jets, which were converted to electricity in 1900, and rewired in 1957. "The Academy of Music in Philadelphia is a beautiful, historic, charming building with wholly unsuitable acoustics for orchestra...The dry, unreverberant acoustics results from the roughly 2,900 audience members, who completely surround the volume of the auditorium, soaking up sound as they sit."
According to wikipedia