Allow me to introduce the 2×2 Starter Block, which represents a 10’x10′ section of a dungeon, castle, or other structure. It is the cornerstone of the campaign, and will definitely be the most widely used part on everyone’s board. Unlike other game terrain, which simply generally provides only a standing wall, often attached to a floor piece, Gridscape™ Blocks represent the full thickness of that part of the dungeon.
How important is the 2×2 block? Take a look at this dungeon below. It would be 3 foot by 3 foot, just to get the scale. The vast majority of a common dungeon would be made up of this one design. As you can see, the second image shows all of the 2×2 blocks in yellow, just to give you a good idea of how common it will be in your setups. My recommendation is to get at least EIGHT 2×2 blocks for every other piece in your collection.