Beyond the height and cost of the project, perhaps the most significant change is that the 2-acre block is no longer expected to be one large building, but instead two: One of about nine stories, and the 800-foot primarily residential tower, separated by a public alley space with retail to provide direct access from Woodward to Farmer Street.

The vision for the vacant Hudson's block has evolved over the years, but the building would still be the tallest in the city, topping the 727-foot Detroit Marriott at the Renaissance Center.

The previous plan called for the Hudson's site includes 1.2 million square feet of above-ground real estate, 250 residential units and 700 below-ground parking spaces in a $775 million development. This one is about 1 million square feet.

Gilbert, through his Rosko Development Co. LLC, has development rights to the Hudson's site, which is between East Grand River and Gratiot avenues and considered one of the most desirable pieces of land in downtown Detroit because of its size and prominent location in a thriving area.

Constructed as an eight-story building in 1891, the Hudson's building was a shopping destination for nearly a century. It expanded to 25 stories and 2.2 million square feet before closing in 1983. It was imploded in 1998.

New York City-based Shop Architects PC and Detroit-based Hamilton Anderson Associates are the architecture firms working on the site's design. Southfield-based Barton Malow Co. is the general contractor on the project.

Specifics about the plan had largely been kept under wraps until February, although sources said in October that multiple concepts have been considered, including one that would bring a 60-story building — which would be the second-tallest in the city — to the site.

The name "Rosko Development" is an homage to Al Rosco, the principal of Adlai E. Stevenson Elementary School in Southfield, which Gilbert and other influential members of his inner circle attended. Just a few of them are Jim Ketai, co-founder and CEO of Bedrock real estate development and management company, and Howard Luckoff, general counsel for Quicken, who is also the registered agent for Rosko Development.

Through Bedrock, he owns more than 95 properties totaling more than 15 million square feet in and around downtown Detroit.