It is a pity that such a unique monument of architecture and military affairs is in a deplorable state. But even now it is an extremely atmospheric structure. If you climb inside, be careful, especially when descending / ascending the turret. By the way, in the local history museum you can see the layout of the fortress in its best years.
All this, of course, is good. But without restoration, the location is absolutely useless. Everything is being destroyed and soon there will be nothing left of the remains of the fortress (
And so yes, you can walk around, get into the story.
I would like to see the 5th fort in Brest restored