Real estate brokers at CB Richard Ellis have been hired to market the more than 800,000-square-foot former Nortel headquarters on North Central Expressway in Richardson.

The two-building Telecom Corridor complex includes a 16-story tower and a three-story, almost 400,000-square-foot research and development center.

Most of the high-profile property is now vacant. Owner Nortel Networks has been in bankruptcy for the last year.

“It’s an orderly bankruptcy liquidation and everything is being approved through the court,” said Gary Carr, executive vice president in CB Richard Ellis’ investment property division. “We are going to try and get it moved by April.”

International defense and high-tech conglomerate Raytheon Corp. recently looked at buying the property. But the deal never closed.

“Raytheon was very close to consolidating and taking the building at one point,” Carr said. “It’s the largest block of office space like this in the metroplex. It represents one of the best corporate relocation potentials in the area.”

The buildings were constructed in 1991 and at one time housed thousands of Nortel workers.

They are within walking distance of a DART light rail station.

Ericsson and Avaya Inc. lease about 30 percent of the buildings.

Carr – who’s working on the sale with CB Richard Ellis’ Russell Ingrum, Jack Fraker and Josh McArtor – said the plan is to sell both buildings to the same buyer.