Or just a menu that lets them choose their language right there on the page somewhere. If you can automatically redirect someone based on their browser language, then you can add a menu with some language names and flag icons next to them too.

Either way, it must like rule 1 of UI design; even if you think you know better than your user does, let them override that choice when you get it wrong.

I've been trying to not assume an Anglo-centric audience, but it seems like this is a popular choice. Almost every major international site, just has English or region-specific English as the fallback.