The 31-story building, once the headquarters of A.I.G., has windows all around and a shape suited to extra corner units. In a city with too little housing, it could hold 800 to 900 apartments.

The four-story building with 102 apartments and a rooftop deck will be the first built with Connect Housing Blocks, modular housing units assembled in a factory on Westerville Road.

The extra building lot, home to the 99 Cent Center, means the mixed-use development in the first block of West King Street would extend from the Hager Building at 25 W. King St. all the way to ...