This report describes a novel research infrastructure, based on a hadron collider with centre-of-mass collision energy of 100 TeV, collecting an integrated luminosity a factor of 5 or more larger than the HL-LHC. It will extend the current energy frontier by almost an order of magnitude. The mass reach for direct discovery will reach several tens of TeV, and allow, for example, to produce new particles whose existence could be indirectly exposed by precision measurements during a preceding e+e- collider phase. This collider will also precisely measure the Higgs self-coupling and thoroughly explore the dynamics of electroweak symmetry breaking at the TeV scale, to elucidate
the nature of the electroweak phase transition. Thermal dark matter WIMP candidates will be discovered, or ruled out. Heavy ion and ep collisions will contribute to the breadth of the programme. As a single project, this particle collider infrastructure will serve the world-wide physics community for about 25 years and, in combination with a highest-luminosity energy frontier lepton collider (FCC-ee, see FCC conceptual design report volume 2), will provide a research tool until the end of the 21st century.