Ad-Deir (Monastery) is the largest tomb façade in Petra, measuring 50 m wide and 45 m high. Despite its name, it was built as a tomb monument and may have acquired its name from the crosses inscribed inside. Like the Kazneh, the structure consists of two stories topped by a magnificent urn. The architectural detail of the Kazneh is not evident in this building.
More info at: en.wikipedia.org/wiki/Petra