Postcard of Manhattan from Woolworth Building. ca. 1914, Bird's Eye View of Manhattan, East River and Brooklyn from Woolworth Building, New York City. Manhattan Island, 19.65 square miles, was purchased in 1626 from Indians for about $24.00, land value now $4,020,000,000, total realty value improvements is $6,075,000,000, an average of $432,000 per acre. The Island has 2,331,542 inhabitants. The lower end has an office population of 400,000: land there is worth from $200 to $600 per square foot