Options for Future Colliders at CERN

We discuss options for future colliders at CERN, after the LHC, which should address the burning problems of particle physics: mass, flavour and unification. We give and comment upon parameter lists for linear e+e- colliders, m+m- colliders and future larger hadron colliders that are being studied in various places. We discuss how particle physics experiments can be carried out at these colliders. We make a number of observations how these colliders might be constructed on or near to the CERN site, and how the existing expertise and infra-structure might best be employed for their study. Finally, we formulate recommendations for action at CERN