What types of institutions make a neighborhood?

According to an article in today's San Francisco Chronicle, a library is an essential neighborhood-making institution. The Mission Bay is "San Francisco's newest neighborhood" with landmark institutions like the Giants stadium on the waterfront, a major regional commuter terminal, and a UC San Francisco campus. Mission Bay emerged as a neighborhood with its most recent amenities: two grocery stores and a new library, the Mission Bay Branch Library. The library is the city's first new library in 40 years and is described as the "public center that established neighborhoods take for granted." Although the Chronicle does not mention of a centrally located park or an elementary school per the Clarence Perry ideal neighborhood unit, today's Cityscape issue does : a 48-acre park and an elementary school are proposed for the neighborhood. http://www.sfcityscape.com/.../mission_bay_overview.jpg