Developers like to slip in a few secrets here and there and while most of the secret were meant to be discovered, some of them like the latest one found in the Witcher 3 was probably not meant to be discovered.
A Witcher 3 player manage to find a secret location where the developers fitted in a picture of the whole CD Projekt Red Development team although you won’t be able to find it on our own without the mod.
The secret was found by a YouTube user Pippo311lp to used the free camera mod to search the Witcher 3 universe. He came across a mountain plain and when he teleported Geralt over, the found a blank canvas in between two pillars. This is no big secret but still significant enough.
By uses the Witcher senses, he was able to uncover the photo. You can watch his video here.