It is traditional in the theater that musicals begin with instrumental medleys of the show's songs, probably because that allows everyone time to get in their seats. But some of these orchestral pieces are quite accomplished. In fact, in some cases (Cy Coleman's On The Twentieth Century, included here, is an example) they provide as much as you really need of a show. So, here are 16 Broadway musical overtures in 64 minutes, gathered by the Metropolitan Opera Guild to lead off its series of Broadway compilations. First up, appropriately, is John McGlinn's 1988 restoration of Show Boat, and we also have music by most of the greats of the American theater, including George Gershwin, Richard Rodgers (note how differently he writes for Lorenz Hart and for Oscar Hammerstein II), Irving Berlin, Leonard Bernstein, Jule Styne, and Stephen Sondheim. One might quibble and note that the likes of Cole Porter, Jerry Herman, Jerry Bock, John Kander, and Andrew Lloyd Webber are missing, but what's here is terrific.