An evening pause: A fascinating and well-filmed documentary from 1935 describing how a British company then built locomotives. Note the lack of construction helmets, gloves, or safety glasses. Note also the number of workers involved. Today most of this work is automated, making it more precise and efficient. Then, however, they did not yet have such technology, and instead found ways to build very sophisticated machines using the skills of ordinary humans.
Hat tip Edward Thelen.