The Mu2e experiment at Fermilab will search for the charged lepton flavor violating process of neutrino-less $mu to e$ coherent conversion in the field of an aluminum nucleus. About $7 cdot 10^{17}$ muons, provided by a dedicated muon beam line in construction at Fermilab, will be stopped in 3 years in the aluminum target. The corresponding single event sensitivity will be $2.5cdot 10^{-17}$. In this paper a brief overview of the physics explored by the $mu to e$ conversion is given, followed by a description of the Mu2e experimental apparatus and the expected detector performance.