Approximately half of the units have been sold to people from the Chicago area, with the other half being sold to people in New York and overseas, such as Dublin, Singapore, Hong Kong, Beijing, Shanghai and Johannesburg. The units range in size from 534 sf to slightly more than 10,000 sf, Metcalfe tells GlobeSt.com. Sales prices range from $750,000 to $40 million, she says.

The building is expected to be the largest residential tower in North America and Europe, and will have the highest occupied floor in the world. Santiago Calatrava is the lead architect and engineer for the building, which will have a five-story glass lobby and underground parking for 1,350 cars. The Chicago Spire will recycle rainwater for landscaping and will use river water for cooling, Metcalfe says. More than 90% of the building's foundation is completed. The building is expected to be finished by early 2012. Metcalfe would not disclose an estimated cost for the project but company officials had previously pegged the price tag of the building at $1.2 billion.

The development will have a 1-acre landscaped public plaza, and the developers are contributing $9 million for DuSable Park, which will be an estimated $12 million project on a three-acre parcel directly east of the site. Perkins + Will is the architectural firm.