Considering the myriad challenges currently facing New York City—the threat of climate change; the crumbling subway system; the fact that the population is expected to top 9 million in the next 30 years—bold plans will be necessary to make the city more resilient in the years to come.

Some organizations are already putting in the work to come up with solutions to these issues; see the Regional Plan Association’s most recent set of recommendations, aimed at improving the health, wealth, and infrastructure in the tri-state area. (They are, however, just recommendations—a bevy of city and state agencies would need to get on board in order to realize them.)

The RPA’s recommendations may be difficult to implement, but they are pragmatic. On the other end of the spectrum, there are the architects and planners who regularly conceptualize all sorts of seemingly impossible solutions to these issues.

In that spirit, New York magazine asked nine different architects—including starchitects like Rafael Viñoly and Norman Foster—to dream up scenarios that would help address some of the largest issues facing NYC right now, including sea level rise, transit deserts, and the need for more green space.

Some of the proposals are pure fantasy; for example, Family New York’s proposed “Super-Tall Parasite Parks,” pictured above, is envisioned as a way to make the current crop of high-end skyscrapers more accessible to the public. “What if this new skyline was accessible to all?” principal Oana Stanescu asked. “What if civic, educational, recreational, and cultural programs — programs that make this city better for everybody — were part of the transformation of New York City’s profile?” It’s a wonderful idea in theory—though in practice, it’s difficult to see developers ceding space on their trophy towers to parkland.

Another fantastical idea comes courtesy of Mark Foster Gage, who proposed what he calls the “East River Valley,” which is, in his words, “epic-scale thinking” to address climate change. His proposal, per New York: “Gage proposes draining the East River and plugging it up with enormous dams, allowing the city and its residents to use the revealed riverbed for parkland, food production, and the construction of ‘massive, next-generation, geothermal wells to power the next century of the city’s energy needs.’”

For the full rundown of ideas, head over to New York.