The FCC-ee is a next generation circular collider proposed for the post-LHC era at CERN. Its principal motivation is to study the properties of the Higgs boson, the prospects for which I shall briefly review. However, FCC-ee will also have the capability of operating at very high luminosity on, and around, the Z pole, and will allow a data sample to be collected five orders of magnitude larger than that accumulated at LEP. I shall present the exciting and powerful physics case for such a programme, with emphasis on the improvements in systematic control with respect to LEP that are required to exploit fully this huge data set. It is concluded that the ability of the FCC-ee to operate as a Z factory adds enormous value to the physics potential of the FCC project.