During the last two years a modified baseline design for the E-ELT was developed. The aim of this revision was both to
achieve a significant cost saving and to reduce risk on major items. The primary mirror diameter was slightly reduced to
39 m and the total height of the telescope also decreased accordingly. This paper describes the work performed by IDOM
under contract with ESO to review the EELT dome and foundations design to match the modified baseline. Detailed
design and construction planning, as well as detailed cost estimates were updated for the 39-metre baseline design. In
June 2011, ESO Council formally endorsed this modified design as the E-ELT revised baseline.
Key redesign drivers are explained and final redesign details of all major subsystems are outlined. In general, the original
compact dome design philosophy is maintained and adapted to the new dimensions. Cost optimisation strategies are
applied throughout the detailed design update process. Special attention is also given to some specific new items now
included in the modified baseline, such as the special ad-hoc seismic base isolation system for the telescope foundation.