Mount Umunhum, San Jose, CA

Mt. Umunhum Road opened to the public in 2017, offering an all-new, twisty climb to the 3,486-foot summit of the peak. Sitting atop the summit is the relic of a decommissioned Cold War military base. Its centerpiece, an 8-story concrete monolith known locally as "The Cube," can be seen from across the South Bay Area. While most of the original Air Force base buildings have been razed, this massive structure was left  as a silent tribute to the Cold War infrastructure that was built on the West Coast of the United States.

During the late 1950s, this "Cube" served as the foundation for the largest rotating military radar ever built. It was a critical node in the Semi-Automatic Ground Environment (SAGE) defense system, a vast network of stations stretching across the West Coast that funneled surveillance data directly to NORAD. The station was constructed as part of a West Coast network that scanned 250 miles out over the Pacific Ocean, keeping watch over United States air space during the Cold War in search of possible airborne nuclear attacks from Soviet Bombers.

At its height, as many as 125 military personnel and their families lived in this "city in the clouds" overlooking the Santa Clara Valley. However, the rise of satellite technology eventually made these ground-based radar giants obsolete. The site was decommissioned in 1980, but it took over 35 years to return the peak to public use.

If you hit Mt Umunhum Road on a weekday morning, the rhythmic, tight-radius curves are yours alone. The view from the top—stretching from the Pacific to the Sierra—is the ultimate reward for the climb. You’ll see two things at the summit- either layers of Bay Area fog or with a bit of luck- crystal clear views to the northeast with Mount Hamilton (Lick Observatory) and possibly even Mount Diablo on a clear day.

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