Kitt Peak telescopes. Located at Kitt Peak, 90 kilometres south-west of Tucson, Arizona, USA, this site has 23 telescopes and is the largest collection of astronomical instruments in the world. Most of them are part of the Kitt Peak National Observatory (KPNO). This view, from the Mayall 4-metre telescope (completed in 1973), includes the McMath-Pierce solar telescope (far left, opened in 1962 and operated by the National Solar Observatory) and the 90-inch Bok Telescope (far right, opened in 1969 and operated by the Steward Observatory, Arizona University). The first telescopes were built here in 1960.