My wife and I recently moved into a ranch house built in 1956. If you look closely you can see where the previous own filled in what I assume to be two little nook shelves with regular old brick and mortar. We were initially planning on covering this up with a mirror but I'm wondering how easily I could restore this by chipping out the brick and mortar the idiot put in? Would it chip out cleanly or would I be left with a mess that would never quite look like it did originally? Any guidance would be appreciated.
Here's a detail of the PO's handy work: