When the hospital opened, research looked like individual doctors noticing trends among their patients or the famous demonstration of ether anesthesia in 1846, but over the course of the nineteenth century, research grew into a major pillar of MGH’s work. Today, the Mass General Research Institute is the largest hospital-based research center in the United States and one of the top ten largest of any type of research center, with $1 billion in annual funding and 9,500 employees conducting research. While much of the research takes place off of the main campus, especially on the Charlestown Navy Yard campus, there is still research work going on in the Bulfinch Building.