Chicago Pile-5 was the last in the line of research reactor that began with the first, which was constructed as part of what project?
Chicago Pile-5: Chicago Pile-5 (CP-5) was the last of the line of Chicago Pile research reactors which started with CP-1 in 1943. Chicago Pile-1: Chicago Pile-1 (CP-1), was the world's first artificial nuclear reactor. Chicago Pile-1:  Its construction was part of the Manhattan Project, the Allied effort to create atomic bombs during World War II.
Manhattan Project