In Citadels, you're looking to build the most grandiose works for the city. To do that, you need... well... works to work with. Just what sort of things can you build? That's what you get a look at in this article of the upcoming rerelease of the game.
From the article:
Citadels is the beloved card game where you compete against your friends to build the greatest city. To do so, you need to choose which districts to construct within your walls. There are a variety to choose from, and they will be the building blocks for your winning strategy