The abandoned location gets a massive boost with this mod.

Thanks to the mod, you can access the previously empty location that you could only access with a console command… only to find nothing behind the closed door, although CD Projekt RED had ideas for The Devil’s Pit. Cooking pot, kits, weapons, as well as familiar NPCs, such as Iorveth and Saskia from the second game will be found here. You may also find a summoning stone (a minor hint: burning), which would allow you to fight a doppelganger of yourself. That alone should be a reason to install the mod!

The mod was made by SkacikPL, the same person behind the first-person mod. You can download it from Nexus Mods, but you have to have The Witcher 3 updated to version 1.31!