The history of Broadway musicals is full of decade-long hits, everything from The Lion King (now in its fifteenth year) to Cats (whose eighteen-year run ended in 2000). But none can stand up to The Phantom of the Opera, that dramatic organ-toned one-night stand that morphed into years-long Broadway love affairs for so many. Today, Andrew Lloyd Webber's masterful production marks its 10,000th show. (It debuted 24 years ago.) Which is impressive and all, but doesn't quite stack up against Agatha Christie's The Mousetrap, the world's longest-running play — one brisk London evening in early January, for instance, it was celebrating its 24,629th showing.