If you want to learn about how high-quality men’s shoes are made, there are few places better to start than this 1930s documentary. It was shot in an English shoe factory and then originally distributed by New York University. Some of the practices today vary from shop to shop, and some of the tools have been updated, but the process - at least on the high-end of the market - largely remains unchanged.
The film even shows the process of gemming, that highly controversial step that has caused an endless number of debates among shoe aficionados (you can see one such debate in this thread at Ask Andy).
The soundtrack (if you can call it that) is highly annoying, so if you watch the film, I highly recommend putting something else on. Here’s one of my favorite albums you can use.