The Very Large Hadron Collider (VLHC) was a proposed future hadron collider planned to be located at Fermilab. The VLHC was planned to be located in a ring, using the Tevatron as an injector. The VLHC would run in two stages, initially the Stage-1 VLHC would have a collision energy of 40 TeV, and a luminosity of at least 1⋅1034 cm-2⋅s-1 (matching or surpassing the LHC design luminosity, however the LHC has now surpassed this).
After running at Stage-1 for a period of time the VLHC was planned to run at Stage-2, with the quadrupole magnets used for bending the beam being replaced by magnets that can reach higher peak magnetic fields, allowing a collision energy of up to 175 TeV and other improvements, including raising the luminosity to at least 2⋅1034 cm-2⋅s-1.
Given that such a performance increase necessitates a correspondingly large increase in size, cost, and power requirements, a significant amount of international collaboration over a period of decades would be required to construct such a collider.