  The Mu2e experiment at Fermilab will search for the charged-lepton
flavor-violating process of a neutrino less muon-to-electron decay in the
presence of a nucleus. The experiment expects a single-event sensitivity of
$2.9\times10^{-17}$, which is four orders of magnitude below the current
strongest limits on this process. This requires all backgrounds to sum to fewer
than one event over the lifetime of the experiment. One major background is due
to cosmic-ray muons producing electrons that fake a signal inside of the Mu2e
apparatus. The Mu2e Cosmic Ray Veto (CRV) has been designed to veto these
cosmic-ray backgrounds with an efficiency of 99.99%, while causing a low dead
time and while operating in a high-intensity environment. The design and
fabrication of the CRV is discussed.
