The Monastery, known as Ad Dayr, is almost 165 feet tall and about 147 feet wide making it one of the largest monuments in Petra. This building is so huge that the doorway is several stories tall! It was built on the model of the Khaznah (Treasury) but here the bas-reliefs are replaced by niches to house sculptures. Crosses were carved into the rear wall of the interior, thus the name "Monastery" or Dayr in Arabic. Its name, like most of Petra's structures, doesn't reflect its function... this building was most likely a Nabatean temple dedicated to the deified Nabatean king Obodas I.