Imagine an apartment building. As soon as you walk through the entrance, you find a multipurpose room. There are tables, chairs, a sofa area, and a kitchen. You head upstairs. On the first landing, next to the doors leading to the private homes, you see a children's playroom and a bookshelf with all kinds of books. On the second, there's a shared office for teleworking and a reading room. On the third, there's a communal laundry room. You reach the rooftop: there are plenty of lines for clotheslines, a vegetable garden, a rainwater harvesting system, and three or four fruit trees.