This design of a vertical structure for Mexico City by Jorge Hernandez de la Garza makes use of modular construction to bring the city some green space without taking up too much precious (basically unavailable) land. The structure can be configured to provide space for public spaces, offices, living spaces, and urban farming. Flexibility is inherent in the design: the layout and size could be changed after construction if needs arise. The modules could even be moved to another location and the land reused. The frame is designed to support solar panels which provide power for the modules and the system also recycles all of its own water.
This is "green" urban architecture with future planning already built in. More architects need to take into account that the current demands that shape their designs will not always be there and new needs will arise.