A distinctive aspect of Rutherford Hill is the extensive hillside cave system. Carved deep into the cliffs behind the winery, the mile-long caves contain over 8,000 barrels of select French and American Oak barrels in which the winery's harvests are matured. Held at a natural year-round temperature of 59 degrees and consistent humidity level of 85%, these caves carefully protect and nurture the wine as it gracefully ages. Rutherford Hill was one of the first wineries in Napa Valley to construct caves and their cave aging system is regarded as one of the most extensive in North America.