Last week, Fermilab took beneficial occupancy from Whittaker Construction Company of the muon beamline enclosure, a large underground tunnel that runs from the Muon Delivery Ring (the former antiproton source) to the Mu2e building and the MC-1 building, which houses the Muon g-2 experiment. Now Fermilab can begin installing the accelerator infrastructure for Mu2e and Muon g-2, such as beamline magnets, cooling water, power cables and vacuum systems.