We report the first detailed study of the phase diagram in the vicinity of a virtual Cholesteric-Smectic A-Smectic C* point in a binary liquid crystal system. The occurrence of the Twist Grain Boundary phase, which is the liquid crystal analog of the Abrikosov flux lattice in type II superconductors, is established by optical microscopy, X-ray and selective reflection measurements. The study affords a direct comparison between the experimental phase diagram and the theoretical scenario as envisaged by Renn and Lubensky.