Providing a welcoming and highly visible front door to the MGH downtown Boston campus, the new Museum of Medical History and Innovation showcases a 200-year history of medical innovation and the hospital’s place in the community. Although the hospital campus occupies more than 15 acres in the city, it previously had no “address” on a principal street. Built on a tiny sliver site, the building’s gleaming copper and glass façade spans a city block, identifying the main entrance to the hospital with a large presence.