I think there's an option to rotate the view of the document.
It might be hidden in a default setup and you'll have to 'customize' the toolbar.

Hmmm... (goes to look)

Yup! You can rotate the view from the 'View' menu in 90 degree increments.
Unfortunately, that only applies to a single viewing of the document- it doesn't change it for the next time you open it.

If you're quick with your keyboard, shft&ctrl&+ or - will rotate the view.