Book excerpt: The San Ramon Valley stretches for 20 beautiful miles under the shadow of Mount Diablo and includes the bustling communities of San Ramon, Alamo, and Danville. Some 113,000 people make their homes here in a scenic area of open spaces, gracious homes, and tree-lined streets. Also here are major business hubs and the winding Interstate 680 freeway. Of course, this valley wasn't always so populous. In the 1850s, while nearby San Francisco boomed and Oakland grew up, this valley remained rural. Mount Diablo became an important early survey marker during California's gold rush, but only in recent decades have the early ranchos and small villages given way to the modern cities we know today.