ABOUT THE HISTORICAL PHOTOGRAPHS Busy, crowded, packed with tall buildings and constantly sprouting more, Longwood Medical Area is like a high-energy chunk of New York dropped into Boston. Named for Longwood Avenue, the main drag, it's a miniature downtown devoted to the single industry of medical research and care. "It may be the highest concentration of brainpower in the United States," claims David Peck, director of facility planning for Children's, one of the numerous hospitals that cluster here. The photographs show Longwood as it looked in 1930 and as it is today. Growth has been explosive. At lower right in the old view is the institution that started it all, Harvard Medical School, which in 1906 moved into a stately range of buildings grouped around a quad. At the top of the old photograph is Beth Israel Hospital. In the new photo, both institutions are so engulfed by later buildings you can barely make them out. Why would so many medical institutions want to jam close together in one small area? It's because Longwood is, in a sense, not multiple institutions but one. Senior employees in its hospitals and research centers often have more than one appointment. They may teach in one place, do research in another, and provide care to patients in a third. And even within one discipline, such as research, equipment and workers may be traded back and forth. All these connections bind the institutions together. E pluribus unum could be the motto. Most of Longwood's current growth is tied to research, and such growth tends to be chaotic and unplanned, because research depends on unpredictable grants from the government or foundations. A single major grant can make an institution want to suddenly erect a whole new building. Longwood grows in a messy way, but it's a great medical center and a crucial engine of the New England economy. And oddly enough, it can be a delightful place for a pedestrian. Busy sidewalks lead to numerous coffee shops and restaurants and, in some cases, to interior malls. There's a buzz of urban vitality. The worst problem is traffic. Planners hope that the proposed Urban Ring of public transit may ease that, but it's years away at best. Longwood's growth, too, puts pressure on adjacent neighborhoods, such as Mission Hill and the Fenway, driving up housing prices and potentially pushing out residents. Longwood's paradox is the paradox of a lot of city planning. How do you tame its vices without crippling its strengths? -Robert Campbell and Peter Vanderwarker, "CITYSCAPES - Vital Signs", Boston Globe, 2 January 2005