A bit late-ish for me to address this but I was reminded when I came back across the screenshot I took.
Murkmire brought us a return of one of the base game side character antagonists, the Ayleids. The ancient "Wild Elves" of Tamriel before the the time of the first Human Empire. It was actually a very interesting reveal toward the end of the main questline when you were in the middle of reliving the events of that First Era Argonian of the Root Whisper, and the contingent of Ayleids appears from within the brush in front of you. It was a beautifully created scene that filled me with a sense of unease and apprehension, and MANY questions.
But what really took hold of me was the moment you exit the Sun Temple proper into a small cave, which then opens up to a massive cavern, with this, at it's center.
I stopped in my tracks and took in the sight, it was amazingly ominous, something that seemed out of place and alien in that setting, that land even. But the gears started to turn in my head. I remembered the earlier dialogue of the Argonians wondering how so many Elves had gotten so deep into Black Marsh, and the answer was staring you in the face. The Gateway. This actually isn't the first time we've encountered this. Remember that area in the Southwest corner of Alik'r? This is what the Ayleids do to expand their Empire's reach, they must send advance teams to the edges of their domain to build these portals and gateways, which then link to their home cities, allowing larger groups to arrive in the new land instantly. And don't even get me started on the Ayleid Nexus.
This shows us there is much deeper intrigue to the Ayleids than we know of, as they are much, much more than the simple enslaving Elves that left fancy ruins everywhere.
CP1,000+ Master Explorer - AvA Tribune - Console Peasant