From the Viaduct Courtyard floo flame, head up the stairs, then up more stairs to your immediate right, so you're almost doubling back on yourself. Head towards the wide stairs ahead of you but veer to the right, so you're standing next to the wall of the tall tower ahead. Take the stairs on your left here and you'll find the eye chest at the end o...

Head to the Library floo flame, run forward toward the book shelves, then turn left and run toward the wall. On your right is a gate. Pass through it, then run forward until you reach the stairs down. At the bottom, turn left, then run through the left doorway until you enter a room with a rectangular cutout in it. Go through the doorway that takes...

Take the Greenhouses floo flame, then turn left. Run forward until you reach the tree and then go down the stairs behind it. The eye chest is tucked away below.