The Treasury is the world-famous monument of Petra, about 2 km from the entrance and thus the easiest highlight to reach. The Treasury is hewn in the rocks, around 40m high and very impressive. It’s not allowed to go in, to search for the holy grail. There are too many tourists coming for the Treasury and it is necessary to protect it from damage. However, there are other buildings in Petra that you can enter. There is almost nothing to see inside, since the buildings are only a few meters deep.
Of course, there are always many tourists at the treasure house, so it can take a while to get a good picture. The off-season is therefore more suitable.
For a view from above there is a steep way to a viewpoint or you can take a longer and safer way to the famous view at the top, which I would recommend. The long way leads past the theater and other impressive buildings. Keep right here and pass the royal tombs. After them the stairs go up. The way up has different viewpoints over the Petra. At the end of the hike you come to a small tent. From which the well-known photos are taken on the carpet on the abyss. The tent charges a kind of entrance fee as you should buy a drink, but you deserved that after the climb anyway. Then it’s time to take photos before going back..
I was up there in the off-season and quite late in the afternoon when the day tourists were already on their way back to the bus and had plenty of time to take photos undisturbed. However, I can imagine that there will be a photo queue in the main season and at peak times.
All in all, the Treasury is absolutely worth seeing and if you visit Petra, you will not get past it anyway. The view from above is also great. Whether the ascent is worthwhile depends on your time and physical condition. You can also be carried up on a donkey, but you should refrain from doing so for animal welfare. If you have 2 days time and no problems with a bit more walking, you should not miss this view.