Movies ask us to suspend disbelief and accept fantasy, never more so than when characters suddenly break into song. What we've learned to expect on Broadway or at the opera house still feels weird in the supposedly more realistic medium of film.

Still, some movies pull it off better than others. It helps if, like in Clint Eastwood's adaptation of Broadway's "Jersey Boys" (opening June 20), the characters are showbiz professionals who have good reason to sing. But even if the characters aren't performers, their songs can express their innermost longings in a way that other elements of visual storytelling cannot.

The theme of the great musicals, whether from Broadway, Hollywood, or locations far flung, is the search for identity. It's something we can all relate to and, if the music is transporting enough, something in which we can happily lose ourselves for a couple hours.

Here, then, are 50 of the greatest films in which only music can fill those empty spaces in our hearts.Best Movie Musicals of All Time