This is perfect. I love the way you made it affect any holding nearby, who may not even realize a myth is occurring, they just pay a tithe and watch as strange new buildings expand their settlement. The loot from the site is awesome too, I like that you can even use their constructive abilities. The helm too is super cool, I love architecture already so it's a really fun idea that you could see future or past builds and really obsess over it in character mechanically. The idea that you would "use" a bridge that does not yet exist is CRAZY, and then becoming the person who eventually builds it for a season, that is brilliant!