By Adam Bluestein

Fifteen years into an unplanned second career as a real-estate developer, Steve Nygren has timed his latest project perfectly. Nygren is the cofounder and developer of Serenbe, a visionary New Urbanist community in Chattahoochee Hills, outside Atlanta. Since breaking ground in 2004, Serenbe has grown to include two villages of about 500 residents. Praised by urban planners, architects, and sustainability geeks alike, Serenbe is, by most accounts, a nice place to live. (You do have to be comfortable with a certain Truman Show vibe, though.) Homes, priced from $300,000 to more than $1 million, sell briskly. Now, with construction of Serenbe’s third village–or “hamlet” in the local parlance–Nygren aims to make Serenbe a great place to grow old. And maybe a model for a new kind of retirement community.