International Saddlebred Hall of Fame International Saddlebred Hall of Fame Home Saving A Major Stable and Saddlehorse History Built in Mexico Missouri in 1887 Simmons Stable is the oldest known building in the United States that was continuously devoted to boarding and training champion American Saddlebred horses. Simmons Stable was a working stable until 2001 and ended a long distinguished history of horses trainers and owners that classified Mexico as the original Saddlehorse Capital of the World. Since 2001 the stable had deteriorated badly resulting in a shifting building with weak side walls a leaking roof and interior water damage. In 2002 a group of concerned citizens formed to create the Simmons Stables Preservation Fund Inc.