Einstein gravitational wave Telescope conceptual design study

This document describes the Conceptual Design of a third generation gravitational wave observatory named
Einstein Telescope (\ET"). The design of this new research infrastructure has been realised with the support of
the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n 211743.
In this document are described the fundamental design options, the site requirements, the main technological
solutions, a rough evaluation of the costs and a schematic time plan.