Originally, the film was to be a seven-episode documentary. After the World Trade Center was destroyed in the terrorist attacks of 11 September 2001, an eighth episode - "The Center of the World" about the rise and fall of the Twin Towers - was made. It aired September 8, 2003.
The radio commercial for the Standard Oil Company at the 25:00 mark of episode 5 is being read by Ken Carpenter, who for years would continue to be heard on a variety of radio programs such as The Great Gildersleeve and Bing Crosby.
Filming took nearly four years and over 170 days including interviews, shooting archival footage, and New York landscapes.