We still don't know much -- maybe it's 2,000 years old, maybe it's 12,000 -- and excavating it will be a challenge, but a challenge that could open up many books' worth of the pages of history.
The structure likely used to be on land, as the Sea was likely lower in that past -- but the scientists and archaeologists can't rule out that maybe, just maybe, it actually was underwater from the start. Ancient humans were inventive as hell, so I wouldn't want to rule that out, either. Either way, PEOPLE LIKE US BUILT THIS, and maybe we can learn more about them. Or at least admire them again for doing this.
My mind, being science fiction-minded, went in a science fiction direction when I heard. There's a detail I like in the novelization Gene Roddenberry wrote for 1979's Star Trek: The Motion Picture: Kirk visits a dam that's been built across the Strait of Gibralter, so humans can finally raise or lower the Mediterranean when needed, and an archaeological dig has taken advantage of that to study long-submerged Bronze Age villages. Heck, I used to live not far from real submerged former towns, because I lived near towns on the Columbia River like Boardman that had to be moved when the dams were built and lakes grew where river used to be. I made sure to walk down a road that disappeared, white stripe in the middle and all, into the Columbia, and try to imagine what used to be there before there was water. Only a few decades had made a difference. Here we're talking about centuries on centuries. And we're still finding signs -- sometimes tiny, sometimes (like in the Sea of Galilee) freakin' big -- of what we used to make.
The world is just awesome. Still.