“What we have is 12 houses,” Matthew Spady said, walking down a ski-slope-steep street in Washington Heights, in Upper Manhattan — 12 houses that have stood together in an unbroken row since the president was William McKinley and the mayor was Robert Van Wyck, who tends nowadays to figure in rush-hour rants on the expressway named after him in Queens. Mr. Spady is worried that the row, described several years ago as “a tiny Alamo” that had managed to avoid demolition when apartment houses were going up nearby a couple of generations ago, may not remain unbroken much longer. He is a project manager with a consulting company and an amateur historian who set up a website for the Audubon Park Historic District . He also organized the Audubon Park Alliance, a loose coalition of residents who share his concern about the rowhouses, Nos. 626 to 648 on West 158th Street. It is the worry of people watching a neighborhood going through its latest transformation. Two of the 12 houses, Nos. 636 and 640, are listed on the real estate site StreetEasy as being under contract for $2.35 million each. There is talk in the neighborhood about offers for […]