QUINCY, Mass. — Barring a catastrophe, few cities get the chance to totally rebuild their downtowns, from the sewer lines deep underground to the sidewalks, buildings, parks and lighting above. But an unusual public-private partnership is allowing this city of 91,000, first settled in the early 17th century and famed as the hometown of the Adams presidents, to try to do just that.

The city has approved plans to raze most of its 50-acre center and replace it with $289 million in new infrastructure and $1.3 billion of new private housing, retail, offices, entertainment, hotels and parking. The private builder, Street-Works Development of White Plains, will pay for the public improvements upfront.

Once Street-Works installs the utilities, roadways, parking and landscaping; builds a number of new buildings and leases 50 to 75 percent of the space, the city will assume responsibility for the infrastructure bill by selling general obligations bonds. Some income from the property will flow to the city to cover interest on the debt, amortize the principal and generate extra money for city coffers.

“We couldn’t afford to do this on our own, this quickly,” Mayor Thomas P. Koch said. But after 30 years of wanting to revitalize a downtown drained of businesses, shopping and housing by outlying neighborhoods, he said, “we’ve established a relationship of trust with Street-Works.” In 2005 the developer started planning what is to be called New Quincy Center. In January it signed a master agreement with the city to codify the plan and set milestones it must meet before Quincy floats the bonds.