Vital records, such as birth, marriage and death certificates: www.nyc.gov/html/doh/html/vr/vrbappl.shtml

TAX PHOTOGRAPHS
Between 1939 and 1941, the city photographed every house and building in the five Boroughs. Copies of these unique images are now available for purchase.
www.nyc.gov/html/records/html/features/taxphoto.shtml