The fantastic temple in the ancient city of Petra, Jordan, also served as an astronomical clock. According to astrophysicist Juan Antonio Belmonte (Canaries Astrophysical Institute), monuments like this were “laboratories” in which astronomical insights into the culture of the Nabateans (Semitic peoples who built Petra) used to be represented.
The position of the doors and the temple itself allow the entry of sunlight in very particular conditions at the winter solstice and in this specific condition the projection of light inside the building ends up performing effects that also had religious significance for the Nabateans, such as the occurrence of aligned beams of light and the incidence of singular placements of shadows of divine statues placed in strategic places for this purpose.
Learn more: http://www.space.com/25318-ancient-petra-monastery-tracks-sun.html