A few hours drive from where I live, we have an outdoor gun museum called Batterie Vara.
This is a german coastal gun fortification which had three 38 centimeters guns. There was planned to be four, but the last one never became operational.
The gun battery is named after Generalmajor der Marinepioniere Felix Vara, who was killed on the British Channel Islands in 1941.
YouTube - bunkertours - Atlantikwall Norwegen 38 cm Batterie Vara 1996
If you want a closer look at the installation I have posted some pictures in the Gallery, the youTube videos are somewhat grainy.
All functions of the gun are still intact.
The generator can be run and the put-put ammo train also running, some 60+ years later:
YouTube - The Battarie Vara Ammunition Train
Regards
RAM