What is the form or structure of the musical The Phantom of the Opera?

Andrew Lloyd
Weber's musical The Phantom of the Opera structurally consists of afollowed
by two acts.

The prologue is set in 1919,
thirty-eight years after the main events of the play, and presents the opera house in disrepair,
auctioning off all of their props and set pieces, including Christine's music box and a
chandelier which the auctioneer comments on as having been connected to the events surrounding
"the phantom of the opera." This opening serves as a kind of frame
tale for the musical. The audience knows that in the end the opera house fades to
disuse, and that there were apparently...