Petra is one of the most powerful wonders of the game, of course largely dependent on the location and of the surroundings of the city which builds it. I built it in Amsterdam in a game with the Dutch where the city was brilliantly placed at the mouth of a long river and was surrounded by 2/3 of desert, some of it desert hills, some flood plains and also plain desert. The rest was tiny bits of grasslands and plains. I played a cultural game and put great emphasis on the quick growth of the population in my cities through advancing in the tradition and liberty policy trees and also my religion which eventually included all possible food bonuses available. With the abundant population and the enhanced production the city was now able to construct almost every wonder available, in spite of the presence of many strong rival capitals. My civilization was thriving with the benefits of the wonders and my culture steadily advanced so that I could utilize Amsterdam's incredible gold potential with the commerce tree, in addition to building all possible wealth buildings there, national treasury, etc. Amsterdam was by the middle ages already turning into an undisputed world capital with the largest population, a huge number of wonders and a gold output that was not matched by half of the other civs in their entirety. A few great buildings and a polder gave some desert tiles absurd yields. As the population grew large enough to work all the superproductive tiles of the city, boosted further by social policies, I started advancing through the freedom tree so that I could ensure that I also have superproductive specialists. I also completed the tower of liberty. Eventually Amsterdam hit a size of 52 as I achieved diplomatic victory in 2015, with the city containing about half of the game's wonders (17). The construction of the utopia project was also well underway as I won the first elections. And no doubt Petra was the early game backbone that ensured the city thrived endlessly boosted on all fronts with gold, production and food from the numerous desert tiles. With the right policies, the religion and maritime city state food bonuses I amplified their effects and eventually made the city into a true masterpiece. But Petra made it all possible, no doubt about it.
A big thumbs up for petra from me !!