Ok, I'm replaying Stormblood with an alt and I'm 99% sure House of the Crooked Coin was built by the same civilization that built Solution 9. Same color, similar pattern. I think the one in Azim Steppe was destroyed by one of the calamities while the one in Tural survived because most calamities are centered around Eorzea. Since the legend of Azim is popular with the Xaela, I'm also 99% sure that Azem had something to do with Solution 9.