  Ground-based gamma-ray astronomy has had a major breakthrough with the
impressive results obtained using systems of imaging atmospheric Cherenkov
telescopes. Ground-based gamma-ray astronomy has a huge potential in
astrophysics, particle physics and cosmology. CTA is an international
initiative to build the next generation instrument, with a factor of 5-10
improvement in sensitivity in the 100 GeV to 10 TeV range and the extension to
energies well below 100 GeV and above 100 TeV. CTA will consist of two arrays
(one in the north, one in the south) for full sky coverage and will be operated
as open observatory. The design of CTA is based on currently available
technology. This document reports on the status and presents the major design
concepts of CTA.
