Real Estate Walnut Creek Democratic Headquarters Space Available for Lease in Walnut Creek December 3, 2012 8:30 am The site of the Contra Costa Democratic Headquarters, formerly the Master Diamond jewelry store is available for lease again on N. Main St. in downtown Walnut Creek. Previous Post The Art Room in Lafayette under New Ownership offering Holiday Saturday Workshops for Children Next Post Judging Restaurants - Nordstrom Cafe in Walnut Creek