However you choose to measure it, Constellation is as big as its name.

The long-dreamed downtown Huntsville development is moving into reality, a massive project that, if expectations are met, will:

Provide a sparkling-new front door to downtown Huntsville

Yield perhaps the city’s tallest building

Result in an investment of almost $100 million.

That's the proposal of developers from both Chicago and Huntsville partnering on a vision that could – again, if expectations are met – catapult the downtown district into a heightened frenzy of prosperity.

"We have greatly enhanced our downtown in recent years with lots of activity, development and businesses and people really enjoy downtown. It's everybody's neighborhood," said D. Scott McLain, one of the developers in the project.

"Yet, at the front door, we've had vacant piece of property for quite some years. That's why we've taken such care to develop this as a mixed-use project. It's a challenging way to develop but it's the most interesting way to develop."

McLain's group, Coldwell Banker Commercial McLain Real Estate, has teamed with Heartland Development Services of Chicago to form Constellation LLC – the company that intends to fill the 25 vacant acres at Memorial Parkway and Clinton Avenue with an array of high-end apartments, office buildings, restaurants and other retail outlets.

Early site work has been ongoing in recent weeks at the site perhaps most easily recognizable as the vacant land around the Spring Hill Suites between the Clinton Avenue and Governors Drive exits off Memorial Parkway.

McLain said the plan is for foundation work on the 219-unit apartment complex – ranging from studio units to three-bedroom units -- to begin in December.

Plans include two office buildings – including a tower on the south end of the property that McLain said could be as tall as 20 floors – along with the apartment complex bordering Heart of Huntsville Drive and a restaurant/retail district fronting Clinton Avenue nearest to the parkway traffic. The Constellation group is talking with restaurants that would be new to Alabama.

McLain projected occupancy at Constellation could begin as soon as 2021.

There will also be extensive surface parking as well as two parking garages. The city of Huntsville is investing up to $2 million in the project to access 40 percent of the parking at Constellation to accommodate visitors to the nearby Von Braun Center.

The city is spending another $1 million on improvements at the Clinton/Heart of Huntsville intersection as well as a road into the development.

The project is not simply about building buildings and making good on an investment, McLain said. With the apartment complex as well as the office buildings, developers are seeking to make the project "architecturally interesting."

"Take the apartments," McLain said. "If you tour the southeast, you'll see a common design for apartments for the last 10 years, a common exterior design. We've tried to vary from that and do something different. It's typically vertical panels of different colors. We've tried to implement curves with the big C for Constellation. In terms of materials, if we're able to achieve this blue metallic material, it will be very striking and very different for the exterior.

"For the retail, we will have a little less control. Retailers have their concepts. With the office building, we have great opportunities to do very interesting things. There's a general architectural idea that has been prevalent in Huntsville for a number of years and a number of examples in research park of what an office building looks like. We would like to push further to have more interesting, probably more modern architecture."

For the office tower, McLain said plans call for it to be at least 13 floors or perhaps up to 20. Even at 13 floors, it would be the tallest building in the city. McLain said he is already getting inquiries about securing space in the office tower.

"I think we will be able to build as high as the site will allow," he said. "There's not a height limitation in this area. So what I say is the height of the building will be limited by physics and economics – both of which are pretty powerful forces."

The office complex is technically a part of the second phase of the project and McLain said “there’s no reason why they can’t be simultaneous. There’s nothing to stop us from starting those right now.”