New York City (and before 1898, the city of Brooklyn) built a series of grand, gargantuan buildings to house public schools around the turn of the last century, many of them designed by world-class architects. In the low-rise residential neighborhoods of Brooklyn, these schools--four or five big stories high--tower over the brownstones as monuments to public education, lending a grandeur to their purpose that the more functionalist schools built in the decades since can't really match. Still, it turns out that these giants weren't always the most efficient or beloved structures to the Board of Ed, who, over the years, abandoned or sold off some of the biggest old schools..
The original schools, however, have found alternate uses around Brooklyn. Forest City Ratner converted the gorgeous P.S. 9, which the NYTimes called "one of the most controversial buildings" in Prospect Heights, into apartments in 1990, sparking local outcry by displacing of the Prospect Heights Neighborhood Corporation (Bruce Ratner and Prospect Heights are now on great terms). A few miles east, old P.S. 83 is now the Bethel Tabernacle A.M.E. Church (though it seems to be falling into disrepair, top photo), with replacement school P.S. 243 sitting next door in its shadow. The United Talmudical Academy has reinhabited several schools in South Williamsburg, including old PS 22 and old PS 168 (second and third photos). Both have postwar-era schools either on the same block or less than a quarter mile away.
The questions I couldn't answer were how these buildings changed hands and why they were replaced. Did the city sell them outright after building new schools nearby? Was that the plan when the new schools were built, or were the schools intended to serve side-by-side with newer buildings and then shuttered when population plummeted in inner-Brooklyn neighborhoods due to white flight and suburbanization? When did the current tenants acquire them, and what's the going rate for an old school? Finally, if they were dropped for reasons other than population decline, what features of these grand old temples of learning rendered them anachronistic or problematic for a new generation of Brooklyn students? There's probably a book (or at least a master's thesis) available on this somewhere, but I haven't found it yet.