So i love to waste time watching YouTube from time to time and is how i stumbled accross the whole starfort/civs phenomenon(thank you Colm!), but i like mostly tanks, guns and big ass war ships, well these navel fortress vids have started to come into the recommendations and they are pretty good and seem well produced and researched, the one about fort Alexander in the gulf of Finland(St Petersburg) is particularly good although presented by what looks like a young boy, he gets right down into the depths of the place. A little bit mainstream but still good info and stunning visuals(drone shots ect).
Anyways i thought i best post a link!