A steep ascent leads past the Pillar of Charles V, a fountain erected in 1554, to the main entrance of the Alhambra. This is the Puerta de la Justicia (Gate of Judgment), a massive horseshoe archway surmounted by a square tower and used by the Moors as an informal court of justice. Alhambra (Calat Alhambra) is a palace and fortress complex located in Granada, Andalusia, Spain. It was constructed during the mid 10th century by the Arabic ruler Badis ben Habus. The majority of the palace buildings are quadrangular in plan, with all the rooms opening on to a central court. The Alhambra was extended by the different Muslim rulers who lived in the complex. Each new section followed the consistent theme of paradise on earth. Column arcades, fountains with running water, and reflecting pools were used to add to the aesthetic and functional complexity. The exterior was left plain and austere. Sun and wind were freely admitted. Blue, red, and a golden yellow are the colors chiefly employed. The Alhambra is a UNESCO World Heritage Site.