The Stars Beneath Our Feet

A boy in Harlem has his older brother murdered. He copes with it by building a giant lego city. He gradually befriends an autistic girl who also likes to build with legos. They have a contest to build a 10 foot tower. However, both of their towers fall. They end up building a big city together. Hers is a realistic model of New York buildings (including their projects). His is a fantasy world with heroes and monsters. He also makes a game with it to help people learn. In the end, they discover that the "wasted" legos that his mom's girlfriend is bringing are actually stolen. The criminal experience helps him to chose not to try to use a gun to attack thugs that have jumped him.
The story deals with coping with grief and difficulties. It also has an underlying theme of how difficult it is to take the projects out of people. They have a big fear of police and snitching and more willing to exact revenge via murder than to snitch on criminals. The projects may have a bunch of people that look "black". However, they are a mix of immigrants from other countries and multi-generational American residents. There are also the mix of various sexual orientations and desires. It may have been more interesting told from the perspective of the autistic girl, big Rose. Her mother committed suicide. She had been teased by others. However, she has a great memory, and can model the city from memory. Only in the end is she taken away for more treatment. (And the book seems to state that her time without treatment helped her.)