During my road trip in Jordan I visited Quseir (or Qasr) Amra when we drove the desert castle loop. We arrived close to 4PM and it was kind of closed already (keep this in mind). We found some man who was ticket officer or guard and they gave us the keys to check the building out. A lot of trust. The building is very small but inside it will take you time to admire all the beautifull frescos. They are so great. Its worth the time to see this place for sure! Some fresco photos on my site