I came across a photo imaging tool today that colorizes black and white photos. Colorize-It.com, part of Algorithmia, makes it easy to add color to photos. I went to the Library of Congress website and found an image of Gay Street, looking north from Wall Street. I assume the photo was taken around 1905 or so.
The first image is right from the LoC. The second shows a partially colorized version. The third shows the final product.
Is it perfect? No. Is it fun? Yes.