August due to local monsoon conditions. History VERITAS was designed to explore the very high energy (VHE) gamma-ray sky above 100 GeV, following up on the success of the Whipple 10 m gamma-ray telescope. The Whipple telescope pioneered the use of an imaging Cherenkov camera, coupled with a large 10 m diameter reflector, to make the first definitive detection of a VHE gamma-ray source, the Crab Nebula in 1989. Subsequently, the HEGRA telescope on La Palma demonstrated good sensitivity above 1 TeV using an array of imaging atmospheric Cherenkov telescopes. VERITAS combines the benefits of stereoscopic observations in an array with large reflectors for a low energy threshold. Compared to the Whipple telescope, VERITAS employs larger 12 m diameter reflectors, improved optics and light collection efficiency, and a finer pixelated camera. Both the recording (using 500 MS/s custom-made Flash-ADCs) and trigger electronics (using a sophisticated three-level system) were significantly improved compared to earlier instruments. VERITAS was conceived in the 1990s, along with three other imaging atmospheric Cherenkov telescope (IACT) arrays: CANGAROO-III, H.E.S.S. and MAGIC. VERITAS is currently the only IACT array operating in the western hemisphere. The first proposal for VERITAS (called VHEGRA at the time) was submitted by Trevor Weekes (Smithsonian Astrophysical Observatory (SAO)) to the Smithsonian Institution in 1995; this proposal described an array of nine 10 m diameter Cherenkov telescopes. In 1998, the first VERITAS collaboration meeting was held at the University of Chicago. In 2000, the concept of VERITAS as a seven telescope array was recommended by the 2000 Decadal Survey in Astronomy and Astrophysics as a moderate-sized project. Delays were incurred due to difficulties with two proposed sites in Arizona (Montosa Canyon at the base of Mount Hopkins and Kitt Peak) and due to a reduction in available funding. The proposal for a four telescope array (now with 12 m diameter reflectors) was favorably reviewed in 2002 and construction of VERITAS started in 2003 at the Fred Lawrence Whipple Observatory. An initial prototype telescope was completed as Telescope #1 and saw first light in 2004. The construction of Telescope #2 was completed in 2005 and first stereo observations started that year. Telescopes #3 and #4 were completed by early 2007 and the first light celebration for the full for telescope array was on 27-28 April 2007. Regular science operations for VERITAS started in September 2007. The construction of VERITAS was largely funded in the U.S.