Most people envision The Treasury as the symbol of Petra. However, the two-story Monastery (seen here from inside a cave) is almost as ornate and is considerably larger at 155 by 158 feet. Built during the middle of the first century, it is believed ad-Deir is a monument to King Obodas I. The “King of the Arabs” reigned from 96 until 85 BC. His cult used the structure as a meeting hall and dining room (called a triclinium) in honor of the deified king. The name Deir stems from the Hermit’s Cell nearby.