We love everything about this window-filled corner, not to mention the view. The picture window maximizes the view, while the double-hungs give ventilation. We also love the low built-in book cases that have function as window seats.
Book Nook in a fireplace that is no longer usable. Very creative use of space. Just make sure to clean that fireplace well before putting any books in there and to seal things to prevent water damage or pests from coming down the chimney.