CCAT (for Cerro Chajnantor Atacama Telescope, or the earlier name, Cornell Caltech Atacama Telescope) was a proposal for a 25 meter telescope with submillimeter cameras. The initiative continues, morphed into CCAT-p (which is now commonly what is meant by a reference to "CCAT"), a scaled down 6-meter design for the same site, which will carry out much of the original CCAT's function and perhaps serve as a pilot for an updated CCAT or CCAT-like ambitious future telescope. The site (in Chile) has an altitude of 5612 meters, an extreme altitude for telescopes, which is very useful for submillimeter observation.
The original CCAT proposal was aimed for construction between 2010 and 2020. It was designed for a wide field of view (20 arcminutes) with wavelengths in the 200 to 3300um range.
Original CCAT's proposed instruments: