Cat that pees in the house?

My cat has been peeing in the house for a whileeee. We always blamed it on the dog because we didn't know cats do that. He will literally pee in every corner of my living room, even with people watching him. It has got to the point where my living room smells terrible, especially when the sun shines into the room and it gets warm out. The smell has also permeated through the floorboards and now my basement smells like pee too! Any suggestions to get rid of the horrible smell? I feel like I have tried everything!