The 11 Most Endangered Historic Places

Juana Briones House, Palo Alto, Calif.
Built by one of the original Hispanic residents of San Francisco, this 1844 home is the oldest structure in Palo Alto, in the heart of Silicon Valley. It was built by Juana Briones, a pioneering woman who was a rancher, traditional healer and entrepreneur. A rare reminder of California's rich Spanish and Mexican history, the structure now sits abandoned, deteriorated, exposed to the elements and threatened by demolition.

• Natural Sites Nominated for the World Heritage List