Each Board has 5 unique Landmarks for you to build and upgrade, which you can access via the Build button on the bottom menu. 🎩
In order to complete a board, you must build each Landmark and upgrade it to its highest level!
If you're the target of a Shutdown minigame and you have no shields, a player can break your Landmark and you'll need to fix it before continuing to upgrade! 

Upgrading a Landmark will cost you money, but each upgrade will increase your Net Worth and grant you a House to put on a random Property Tile. 
Note: Fixing a Landmark will not grant Houses or Net Worth points.