In the second chapter you will be introduced to building. It is closely related to some parts of the story, and also works as an additional extension of the game which improves some actions. Outside of the missions you can most often build Call-In Points, points where you can summon any unlocked vehicle for free. There is a total of 65 Super Builds in the free play mode to be built in the game.
There are also other in-game structures, such as ramps, which will allow you to perform a jump with a vehicle and e.g. get across to the other side of a river much faster.
To build you need special bricks, which are marked with a square on the interface, below the well-known studs – which serve as a currency. The second type you can gain without any problems: they are scattered on roads and sidewalks, are hidden inside of objects, you receive them as a reward for completing certain tasks or activities.
There are only two ways of acquiring the square bricks: during the destruction of larger objects, while you collect the blocks which drop from them (the preferred method), or by collecting the Super Bricks that are scattered around town, such as the ones seen in Chapter 2. The bricks in question come in two categories, small (equivalent to 1,000 blocks) and large (10,000 blocks). Take your time at the beginning, and do not worry too much about collecting them - many of them are well hidden and special skills are required in order to get to their locations.
After completing the second chapter you will get access to a special scanner, which can detect super bricks, that are invisible to the naked eye and mark them on the radar. The range of the scanner is unfortunately quite limited.