The Wikipedia has (amongst more): "A line of walls that encircled the entire city defended Ani. The most powerful defences were along the northern side of the city, the only part of the site not protected by rivers or ravines. Here the city was protected by a double line of walls, the much taller inner wall studded by numerous large and closely spaced semicircular towers."

I show pictures of that northern part (and a few taken when entering between inner and outer walls).