I have two cats. A few months ago one or both of them started eliminating in the entry way to my house. I have a split level house, sort of, where there is a mud room at the bottom, then stairs to the main floor, then stairs to the upper level. They have had a litter box on the upper level (their "room", the laundry, with the litter box and their food dishes) and another litter box on the main floor behind a couch.
Up until a couple of months ago it hadn't been a problem. When it started I treated the area with Nature's Miracle and some Urine-Away spray I got from the vet. When that didn't stop I put a small litter box down there, then they started eliminating in or outside of it. However this made the whole house smell terrible so I started slowly moving the box. They responded by "going" right back where they used to. I don't know what to do. They are slowly destroying that area.