from Wikipedia:

Qasr Kharana (Arabic: قصر خرّانة‎), sometimes Qasr al Harrana, Qasr al Kharanah, Kharaneh or Hraneh, is one of the best-known of the desert castles located in present-day eastern Jordan, about 60 kilometres (37 mi) east of Amman and relatively close to the border with Saudi Arabia. It is believed to have been built sometime before the early 8th century AD, based on a graffito in one of its upper rooms, despite visible Sassanid influences. A Greek or Byzantine house may have existed on the site. It is one of the earliest examples of Islamic architecture in the region.