In a rural corner of the San Francisco Bay Area, a tech investor has a vision to build a walkable city atop farmland and golden rolling hills. The proposal could help solve twin crises confronting the Bay Area: a shortage of housing and the growing threat of climate change. But the project has generated controversy from the start, and getting it off the ground has been anything but easy. KQED's housing affordability reporter Adhiti Bandlamudi follows along to see what it takes to build something of this scale in California.