Petra, Jordan. Ad Deir (the monastery) is one of the most famous buildings of the ancient city of Petra. It's the biggest monument, the facade is 45m large and 42m high. It is associated with funerary rituals dedicated to the deified nabatean king Obodas I. The urn topping the building is 9m high. The building was inhabited by monks in the middle-ages, hence the name "the monastery" today.