I first walked along the outside of the wall from Saray Gate. There was a small path, that quickly petered out and became a bed of brambles. After falling flat in these brambles (my foot got trapped behind one offshoot), struggled on for a while and then decided to backtrack. I walked on the inside of the wall (without actually seeing it, or being forbidden by notices to approach) until I got to the Yenişehir Gate. From there things got much easier.