There are 15 levels that you must achieve the Special in to unlock this trophy. You can achieve the Special in either Story Mode or Free Play. You will get the Special in most of the levels in Story Mode without trying. If you happen to miss one or two, I missed 2 out of 15, then buy some red brick multipliers and you will have no problem achieving the Special in Free Play. See the Welcome to Bricksburg Trophy for the locations of the Red Bricks. The stud requirements for each level are as follows:
1) Bricksburg Construction: 105,000 studs
2) Escape From Bricksburg: 80,000 studs
3) Flatbush Gulch: About 110,000 studs
4) Flatbush Rooftops: 210,000 studs
5) Esacpe From Flatbush: 48,000 studs
6) Welcome to Cloud Cuckoo Land: 75,000 studs
7) Attack on Cloud Cuckoo Land: 75,000 studs
8) Escape from Cloud Cuckoo Land: 35,000 – 40,000 studs
9) The Depths: 120,000 studs
10) Infiltrate the Octan Tower: 205,000 studs
11) Put That Thing on the Thing: 100,000 studs
12) Broadcast News: 100,000 studs
13) Back From Reality: 100,000 studs
14) Bricksburg Under Attack: 120,000 studs
15) The Final Showdown: 30,000 studs