Why is /blog not displaying /blog/index.html? So basically, my url is mysite.com/blog which should apparently lead to /blog/index.html which is stored under templates/blog/index.html. As far as I can see I don't need to set up any routes to make it work and it should be happening as standard. I'm working in a multisite environment, and may have done some damage there? I basically need to know where the error will be coming from, .htaccess/index.php etc...

Thanks!
Check for a blog.html file in the root of templates, craft would go to that first then check for a subfolder.

You can read more about the process that Craft follows when deciding how to handle a request.