Today was open bunker day in the Netherlands, where a whole line of old German bunkers along the Dutch coast are open to the public, and as I happened to be in The Hague today... I finally saw Seyssinquart's* bunker on the inside. It's a terrifying claustrophobic thing, even though it literally looks like a giant traditional farm shed on the outside. It's labyrinthine, and the hallways are tiny and cramped. After the war it was repurposed and made into an ops center by the military during the cold war, and it was used to register troop movements by the USSR as well as manage military communications. As a result, the interior mostly dates from the 60s and 70s. Later it was used for military exercises and some of the walls are covered with paintball residue before it was finally closed off and left abandoned (but still heavily guarded). I tried to fit all my impressions of the thing in one drawing, and I had some fun with fosca markers.
*Seyssinquart was the Reichskomissar for the Netherlands, and he lived in a villa in Clingendael - an old estate that is now a huge park. This bunker is on the outskirts of the park and it was connected to the villa by means of a tunnel.