Swedish to English Art/Literary History

Hello

The article is about the Roserberg Palace.

They are talking about the wings of the palace, namely Kavaljersflygeln and Teaterflygeln

The first two I gave in Swedish but translated in () as it seemed appropriate and helped explain the furnishing and decor

But now I'm stuck with 'Källarbacken'.

What does this suggest to a Swede? Is it "basement hill" or more "cellar slope" or whatever? I can't find the historical origins to this name.

Yes, I know that common names are not always translated but I've had to translate the first two.

Thanks