The view was astounding. You could see the whole city and then some. Within the citadel is a museum for the Resistance and WW2, a museum about Franche-comté history, a restaurant, an insectarium, aquarium, noctarium, and zoo. We decided to save the museums for another day as they are each three stories, we didn't know how my leg would hold out and I was looking most forward to the zoo.
We started out with the aquarium, which was two large rooms filled with prawn and fish indigenous to the Doubs river. There were trout, loaches, bass, and a lot of different types of perches. Outside there was a koi pond and you were allowed to pet them. When I say "rooms", it was really like two small buildings. The awesome part about the citadel is they incorporate the old fortress into all their pieces, so the aquarium is what used to be a small courtyard which now has the koi pond and water garden and two small buildings to the left are the rooms with the fish and prawns.
I took no pictures of the noctarium because it's so dark inside, but it wasn't much to see anyway. Nocturnal animals indigenous to the area (so basically just mice and rats) are in this small building that used to be for storing gunpowder, and it's completely dark with a little bit of blue light to see your way through. At night time, they have normal light on to simulate daytime, with the theory that the animals will come out during the daytime because they think it's night. The only ones who were active were the rats. They also had some stuffed foxes and weasels since I guess an old gunpowder storage building isn't a suitable habitat for live ones.