This is something you must do. We did the 7 km walking tour, one of the highlight of this year’s trip. You need to book in advance if you want to do the 7 KM (each way) as it requires a guide, it is pitch black and huge. You can do the first 1 KM that is all light up but you will miss the main attraction if you don’t do the 7KM.
http://yourshot.nationalgeographic.com/photos/5950490/
Visited April 2015