Having the Tearing Column on your right hand and pass through the gate near it. Go further and pass the next one too. Here you can see a screen on your left where there is a video show about Hagia Sophia. When you arrive here turn left. You will see pictures and maps hanging on the wall on your left. In the middle of the hall, you will see the snake-Patterned Pool (or Perirrantirio). Listen to the story of the 22nd point of interest.