What is the best place to study voice (opera) outside the US?

Don't forget Austria--in particular the Universitaet Mozarteum Salzburg and the Universitaet Salzburg and several good schools and universities in Australia. Really, with just a bit of checking you can locate good schools in just about every region of the world. Now, the catch. Really good music programs won't take just anybody. You have to meet certain strict criteria and have a lot of future potential for them to even want you as a student. Ultimately, what makes a great opera singer is both natural talent combined with the proper training to make use of that talent.