What color is Blueprint, Apartment House, Rue Heine, Coude Transversable, 1926 ?

Source Crayola® CSS3 CSS4
#557d9e
 
#5d76cb
indigo
#4682b4
steel blue
#4682b4
steelblue
#8da4b1
 
#979aaa
manatee
#a9a9a9
dark gray
#a9a9a9
darkgrey