By 2030, two-thirds of the world’s population will live in cities, and most will be poor. Our cities–designed in a time when neither of these facts were true–are struggling to adapt to this change. But if we want our cities to do more than simply expand haphazardly to accept their new residents, it’s time to start planning.

That’s why a new exhibit at the Museum of Modern Art, which shows how six teams of architects and designers tackle the problem of growing income equality in cities from Lagos to New York, is so fascinating. The design teams spent 14 months looking at urban interventions in their own cities, and then used that inspiration to create new visions. “The teams were learning from informality, these spontaneous bottom-up interventions,” says curator Pedro Gadanho.

On a Tumblr for the exhibit, the museum is collecting existing examples of “tactical urbanism.” But they saw room for new ideas–and for architects to step in as intermediaries between citizens hacking solutions and cities making official plans.

“This is really also about the changing role of architects and how they can sort of function as connectors between top-down planning and bottom-up initiatives,” Gadanho says. “That’s quite important. We’re even questioning what the role of architects is in cities in these processes for urbanization.”

NLÉ, Lagos, Nigeria and Amsterdam, Netherlands; Zoohaus/Inteligencias Colectivas, Madrid, Spain

Home to around 20 million people, the Nigerian capitol is the fastest-growing city in the world. As many as 250,000 people live in the sprawling Makoko slums. Architects took inspiration from the slums’ floating architecture–like this floating school–and created well-organized floating neighborhoods with solar-powered community centers.

“The collective actively looked for prototypes of urban objects and structures that then can be transformed into something that can be used at a larger scale,” says Gadanho. “So they went into the city, they looked at these examples, identified them, cataloged them, and they turned them into part of that vision for the future.”