How to register/use MVC Areas with 5.x

How do you register an MVC 'area' with Sitefinity 5.1+?

This useful blog post gets you part way there, but since the area is not registered, it passes in a full path to the view, rather than simply return View();

example:
   return View("../../Areas/Demo/Views/Demo/Index");

blog.falafel.com/.../mvc-comes-to-sitefinity-5.1

Note that my project does not include a global.asax by default. Where are the MVC routes located by default in Sitefinity 5.1+? Do I need to add a global.asax?

Suggestions?