We've had some problems with the puppies being a little too enthusiastic when greeting the cats, and the cats have not enjoyed this, so we're going to build a set of paths on shelves so the cats can go from room-to-room without having to deal with the dogs.
In one of the rooms downstairs we're going to cut a hole in the wall above the doorway, and that room is where the litter box will go. The door will stay closed in order to keep the dogs out.
In the kitchen, one old desk and the top shelf on each of two sets of shelves will be for the use of the cats. A ramp will lead up to the top of the doorway between the kitchen and the living room. There is no sheetrock on the 2x4s above the doorway, so the cats will be able to go through there to get to the main shelf in the living room. That shelf will extend along the longest wall in the living room, with one shelf leading to the room with the litter box, and one shelf to the railing next to the sixth step of the staircase leading to the second floor. A gate at the bottom of the stairs keeps the dogs from going upstairs, so the cats will be able to visit there without the fear of thundering puppies twice the size of the cats.
The kitchen piece is almost complete (for version 1.0 of Cat World). I have to work two jobs tomorrow, but I'm off Thursday and Friday, so I hope to complete the project then.
While I was waiting on hold to talk with a human at the IRS, I decided to put some food out for the dogs. I set the full bag of dog food on a chair, and walked away to get the bowls. When I turned around I saw the bag slowly tipping over, spilling much of its contents onto the floor. Fortunately I had help cleaning it up.