The so-named "High Place of Sacrifice" is a modestly challenging hike up from the valley floor. The climb begins in the large, open area fairly close to the theater. Coming from the "Treasury" building at the entrance to the city, you find the trail around the corner and to the left after the valley widens greatly but before the theater.
The sandstone steps are extremely worn in places and can be very slick with the ever-present, extremely fine sand that covers everything. Be certain of your footing (especially on the way down), and expect to spend at least two hours. Donkeys can be rented if you do not want to hike, but do be aware that unless you commonly ride your backside is likely to be quite sore.People in their 40s and 50s commonly hike to the top and there are many places to stop and catch your breath. Possible to make it to the top in 20 minutes with a very good cardio workout. Coming down is certainly easier, but again be very careful of your footing!
Like nearly everything outside of the U.S., this is a "NEVER in the United States" attraction. There are no railings and lawyers would describe the steps and trails as "treacherous" at best. There is nothing or nobody to prevent you from leaving the trail areas to explore even more difficult to access places. Be cautious and be aware of your limitations!
Also like many ancient places, the age and purpose are not clearly understood. This is obviously a very special place for people for many, many centuries and numerous civilizations.
Once at the top, the views are stunning--especially at the far northern end where you have a beautiful view of the heart of Petra.
The actual "Place of Sacrifice" was certainly a place of ritual, but the rituals themselves are unknown. What is called "the table" is actually a fairly large, shallow, carefully excavated depression. Perhaps a rain gauge?
Surrounding the "Place of Sacrifice" are many other man-made things including obelisks, caves, carvings and a large ashlar building now in complete ruin.