Bookshelf Hiding Old Window

We made some additions to our offices and there were two windows that needed to be boarded up. I made this bookshelf to fit into the gap at the window. There is one of these bookshelves on each side of the window. They rest on the window sill and are also screwed into the wall in numerous places.

The bookshelf is perfectly suited to this space and nobody would guess that a window still exists behind the bookshelf.