Kitt Peak Observatory. Some of the telescope domes at the Kitt Peak Observatory in Arizona, USA. The large dome holds the Mayall 4-metre telescope. The four smaller domes on the hillside below it contain (from left to right): the 0.5-metre telescope; the 2.3-metre telescope; the 0.9-metre Spacewatch telescope; and the MIT/ETC telescope. The Mayall 4-metre is the largest optical telescope at Kitt Peak. The summit of Kitt Peak is 2062 metres above sea level. Observatories are built at high altitudes to prevent distortion to incoming light from atmospheric interference. The site was chosen for an observatory in 1958, and in 1998 it has 14 research telescopes in operation.