FACET will rebuild the beamline in the sector 20 region of the linac tunnel to compress and focus the beam to less than 100 femtoseconds in duration to less than 10 microns transversely. An additional 30 meters of beamline provides a general purpose experimental area with facilities for mounting experiments and safely dumping the beam. Experimenters will access the tunnel through a new staircase located in sector 19 and shown in green.