We present the *C*ROSS (Cryogenic Rare-event Observatory with Surface Sensitivity) *C*ryogenic *U*nderground (C2U) facility installed at the Laboratorio Subterranéo de Canfranc (Spain). It consists of a low-radioactivity, pulse-tube-cooled dilution refrigerator where scintillating macro-bolometers are run and read out via low-noise room-temperature electronics, to study the neutrino-less double-beta decay of $^{100}\mathrm{Mo}$, $^{130}\mathrm{Te}$ or $^{116}\mathrm{Cd}$. Since the commissioning (mid-2019), we performed three long-living runs (up to 5 months duration), operating several detectors which reported superior performances in terms of stability, running duty-cycle and energy resolutions. The C2U facility is about to be upgraded with a) an extension of the present internal/external shielding, b) the installation of an anti-radon system, c) a muon veto.