It is one of the largest monuments in Petra, measuring 47m wide by 48.3m high. It was built on the model of the Khazna but here the bas- reliefs are replaced by niches to house sculptures. A columned portico extends of the façade; the interior is occupied by two side benches and altar against the rear wall. It was used as a biclinium for the meetings of religious associations. And dates to the early 2nd century AD, during the reign of King Rabel II. In the hall was reused as a Christian chapel and crosses were carved in the rear wall thus the name “Monastery” (Dayr in Arabic).