Creating the Canvas

I call my house "The House of Three Cats" since my 3 animals are the founding felines of the place. We are up to five (Liz has 2 upstairs) but they are the stars of the show. The idea was that this would be a mural of my three cats as the focal point. So I began to sketch some ideas. Would they be in a garden peeking out of bushes and half hiding behind giant flowers? Or Chagall-like flying around in a pale blue sky? No I wanted something to reflect their worldliness so I would have them in front of a New York skyline and a Russian one too to reflect their original home (Russia) and their American home (NYC).
Meanwhile I got busy prepping the "canvas" by scraping all the old paint off, filling in cracks and then painting white with masonry paint to seal up my "canvas". OK we have the main wall figured out, but what about the other spaces? I can't just leave those white--they'll get dirty! Well it should all represent something neighborhoody not just random birds or flowers. Back to the art studio then.