I had an older cat that peed in MANY places he shouldn't around the house, particularly on the landings at the bottom of stairs. Cat has passed, and we replaced the carpet in the basement. One of the remaining two cats still urinates at the bottom of the main carpeted staircase. I doused it with Nature's Miracle, let it dry, baking soda, vacuumed, and then covered the area with carpet plastic (like you'd use during construction). She is STILL urinating there every few days or so right on the plastic, and uses the litter boxes the rest of the time. It's easy to clean up, but I don't know what else to do to change her behavior. Vet says she's perfectly healthy. Other than putting a litter box right on the landing (um, no...), any ideas?