  The Cherenkov Telescope Array (CTA) will be the next generation of
ground-based instrument for Very High Energy gamma-ray astronomy. It will
improve the sensitivity of current telescopes by up to an order of magnitude
and provide energy coverage from 20 GeV up to 300 TeV. This improvement will be
achieved using a total of 19 and 99 telescopes of three different sizes spread
out over 0.4 and 4.5 km$^2$ at two sites, respectively, in the Northern and
Southern Hemispheres. After a concerted effort involving three different
large-scale Monte Carlo productions performed during the last years, here, the
baseline layouts for both CTA sites that should emerge after several years of
construction are presented.
