Tombs, why not Temples?

I was really wondering why were pyramids made as Tombs not Temples?( no really it was on my mind for quite a while.) I think they were made like that, because 20 long years just to make 1. Also the tunnels they made instead of leading to rooms they lead to tombs. I think if they wanted to make them as temples they could open the walls up so that the pharaohs could see their kingdom. I don't why I just suggested that they're awesome the way they are.