Apartment envy is not unique to New York City, but it is certainly one of the closest watched real estate markets in the world. As the twentieth century began, savvy real estate developers worked to create ever-grander buildings around Central Park and other prominent locations around the city. This digital collection from the New York Public Library brings together 1300 images that depict elevation views and floor plans for middle and upper-class apartment buildings from the city's pre-World War I residential building boom. The materials include items, diagrams, and photographs from volumes like 1908's "Apartment houses of the metropolis" and "Modern plumbing, no.6." from 1911. Overall, it's a fun site and urbanologists, historians, and lovers of New York City will find it most enjoyable.