Walking through the woods and boom: Bofors
Marcus Edin and friends recently got a chance to check out an ~almost~ fully working 1941 Bofors M/24 12cm/50 cal gun and some surrounding bunkers in quite good condition in Sweden.
Apparently, the last service was performed on these in 1988 as the Swedes kept these low-tech but still effective coastal guns in operation through the end of the Cold War. After all, it would track that these were still capable of zapping an interloping Soviet destroyer or amphib that came in close enough and they were immune to EMP in the worst-case scenario.
Marcus has a great video with a closer look.