This plays the traditional tune London Bridge is Falling Down, and is a simple example of how you can use Scratch to play music. I've also included a slideshow script with a couple of photos of London Bridge, but you might want to use this and add in your own photos of London.
This is an example game from the book Scratch Programming in Easy Steps by Sean McManus. The book shows you how to convert sheet music into Scratch music. More info here: http://www.sean.co.uk/books/scratch-programming-in-easy-steps/index.shtm