So I am working my way around the south of the map clearing up the question marks in Velen. I've noticed the question mark which I pictured below, but having done a near full circle of the mountain, I cannot find a path up this mountain.
With the use of spoiler tags where necessary, how can I visit this location? I'm currently lv11, and am wondering if it's a story location I'll visit later.
This is a location you can only visit during the main quest. It's a pretty late quest, closer to the end of the game.
As far as I know you can't get there before the quest. I did read about a few people managing to get there, but running into glitches as this wasn't intended. I would just ignore that location, it'll come up at some point during the main quest.
It is involved in the main questline late in the game. Any attempt to get to this location will involve you hitting invisible walls or the game telling you "You reached the limit of this area, turn back."
I was even able to get there (lvl 9). The question mark is obelisk of power, but aside of that there is nothing. :( Some loot in the cave on the way back, but nothing "meant for higher lvl player". Took me tens of minutes to find a way up. It wasn't worth the time.