Luckily there are no spoilers for the mechanics, but Cathedral looks like it's a landscape-shaped thing, maybe a Project?
PREDICTION: Projects are special card-shaped things that can be bought over several turns. Once you have bought it a sufficient amount of times, it grants a massive benefit. One project is used per player.
The first time you buy a project, place it in front of you and place your project token on the "1" space.
Random Unbalanced Example: Cathederal: $4 Project.
Move your project token to the next space.
If your project token is on space 4 or more, at the start of each of your turns, You may trash any number of cards from your hand.
Yes, I stole this idea from Wonders in Seafarer's of Catan, though I think it could really work in Dominion.