Thirty-seven years after the U.S. Air Force shut down a mountain-top radar station in the hills south of San Jose that scanned the skies for Soviet bombers during the Cold War, the summit of Mount Umunhum is finally opening to the public this week as a new park, with stunning views of San Francisco Bay, Silicon Valley and Monterey Bay. The Midpeninsula Regional Open Space District, a public agency that owns the 3,486-foot peak in the Santa Cruz Mountains east of Los Gatos, spent $25 million over eight years on the project. Supporters say the new summit, which visitors will...