Mayo Clinic first took root in farm fields near Rochester, Minn., in the late 1800s. It grew from the medical practice of a country doctor, William Worrall Mayo, and the partnership of his two sons, William J. and Charles H. Mayo—affectionately known as Dr. Will and Dr. Charlie. The brothers’ innovative ideas and tireless work in learning and creating new surgical techniques attracted international attention. Physicians from around the world came to watch the Mayo brothers perform surgery. The Mayo brothers invited other doctors to join them, forming teams of medical experts. Today, Mayo Clinic—one of the world's oldest and largest multi-specialty group practices—comprises more than 45,000 physicians, scientists, nurses and other staff at its three locations in Rochester, Minn., Jacksonville, Fla., and Scottsdale, Ariz., and its regional community-based health care practices.