Sanctum of the Twelve?

[Ryuseki]

This place has me pretty intrigued, at first I thought it might be some kind of sealed weapon/sealed temple like something out of FFV, what with the giant stone circle of symbols, a shrine dedicated to each of those symbols in the area, and the giant sealed door with all of the symbols on it.

Then I noticed that the symbols represented the gods/goddesses of Eorzea, (Rhalgr the destroyer, so and so forth)

Anyone have any clue what this might be for future content?

[Unaki]

Its the main temple one would go to when they wish to pray to the Twelve for guidance. Its kind of like a Mecca of sorts. I doubt it will serve much of a purpose at all until 3.0 or later but if you look at where the Scions pray to the Twelve to summon the prison of light in "End of an Era" it looks like Thancred was praying there.

[Fleurette]

Its the main temple one would go to when they wish to pray to the Twelve for guidance. Its kind of like a Mecca of sorts. I doubt it will serve much of a purpose at all until 3.0 or later but if you look at where the Scions pray to the Twelve to summon the prison of light in "End of an Era" it looks like Thancred was praying there.

Not exactly! The Sanctum of the Twelve is simply (from what I understand), a cathedral built in honor of the Twelve from a very long time ago, only recently found in the Shroud after the Calamity. The NPCs there are currently trying to renovate it so that we can access it in future patches; the devs mentioned a while ago that the main purpose of it is for character marriage later on.

As for Thancred, he was praying at the Arrzaneth Ossuary in Ul'dah during the events of "End of an Era".

[Enkidoh]

Fleurette is right from what I understand - the cathedral's purpose is simply for in-game marriages which will be available sometime in the future.

And yes, in the End of an Era trailer the Archons were all praying at the Deity Stones that were found in different areas, and which were already accessible to the player - they were not at the Sanctum of the Twelve at it was still abandoned and forgotten at that point in the storyline.

[Vydos]

I'm pretty sure S-E said that it will be the place you can get married. Might also have other uses but that's what they said about it.