From "MGH Campus: Museum, Ether Dome and Other Historical Points" by Yonward User Massachusetts General Hospital
The Ether Dome was Mass General's surgical amphitheater between 1821 and 1867. Dr. William T.G. Morton, a Boston dentist, made medical history here in Oct. 16, 1846, when he administered ether anesthetic to patient Gilbert Abbott just before Dr. John Collins Warren removed a tumor from his neck. Abbott slept comfortably during the operation and upon awakening announced that he had felt no pain. News of this first public demonstration of surgical anesthesia spread rapidly, transforming medical practice throughout the world.