The optional excursion, Petra at Night, is a personal choice and something to consider. It’s $18 and for me was worth it. You walk a mile downhill to the gorge on gravel/rock path and then through the gorge with its walls of up to 500 feet over more gravel and Roman paving stones in darkness lined with luminaries. It is advisable you have a flashlight and I must say in spots the flashlight could save you a sprained ankle or worse.
Looking up through the opening the walls create you will see the desert skies with billions of stars. It is stunningly beautiful. Viewing the walls and rounded stone I thought it resembled clouds at the top but that is an illusion. The moment the opening to the Treasury is reached the site of hundreds of luminaries on the floor in front of the facade is awe inspiring. The candles are the sole lighting for the performance. There is chanting and flute playing, then a narration by a local. I wish I could tell you what he said but it was difficult to understand. That did not diminish the sight in the least. I took a small tripod and set it low to the ground so the crowd would not hang me but since it was low I shot a lot of heads. The shots are not great but they will let me remember the moment.