Humpty Dumpty can't sit on the wall because he was an egg and egg roll over.

Well I only know three so sorry but I know if you go into the hospital and sit on the wheelchair and then click on the wall behind you you are on the wall and I know that in Chez Bruno There is a chair near where you hang your coats by the wall and you sit on that and then click on the wall next to you and you are on the wall and the last one is the ice cream parlour there is a chair near the right wall and you sit on that and then you click on the wall next to you and you are on the wall

Yes, the GE Spacemaker CuFt Over the Range Microwave Oven can sit flat against the wall.

on a wall

on a wall