So, all the talk about the Crestwood cave made me go back there and really take a good look around and you know......I think it has to be the site of a very significant event leading to the fall of Arlathan.....and an event featuring our dear Solas.
Because think about it, Solas just telling Lavellan who he is and all that honestly would come off as...well, crazy. I mean, even if she didn't freak out because he's the big, bad Dread Wolf I would imagine that the average Lavellan would at least say "Prove it." So, in order to do that he takes her somewhere the Veil is thin and easy to access the Fade and may still have spirits acting out the events that took place there.
Now what event took place there, I don't know. The murals that go around the cave are the red templar looking character, the zombie looking elves, a dragon and some mounted elves that look like they are riding into battle. So, the dragon kinda says to me that maybe it was something to do with Mythal? Or maybe even that story of the sinner who belonged to Dirthamen. I mean, supposedly the sinner took the form reserved for the gods or whatever at the urging of Ghilan'nain....and I think the statues pretty clearly show this must have been some sort of shrine or something to her.
Also, in regards to the murals, the only people it makes sense to me to have painted all the murals everywhere are elves who were from very low slave ranks. I bet everywhere we see the murals painted were actually historical sites that these freed slaves may have gone to to tell the stories of what happened. And since they probably did not know how to read or write, they painted murals instead to tell what happened. Abelas seems to know how to read and write, and probably the other sentinels as well, but I'm talking these were the low, low slaves.
Another interesting note, is that outside the cave are statues representing Falon'Din and Fen'Harel. There is also the astrarium thingy for Kios outside.
Either way, I think whatever the event was Solas must have wanted to show it to Lavellan....and it is such a bummer we didn't get to see it. Because something tells me whatever it was, seeing that one event would fill in a lot of holes for us. I'm not saying there still wouldn't be a ton of questions afterwards....but I think we would understand a lot.
I think Bioware should show us in a DLC. I'm just sayin'.