MILWAUKEE---Northwestern Mutual will announce plans Thursday to build a high-rise office building at its downtown campus.

The $300-million tower would replace an existing 16-story building at Mason and Cass streets.

The company announced last year it would raze the building because of high maintenance costs.

The height of the new building and drawings have not been released.

Northwestern Mutual employs more than 3500 people downtown and 2000 at its campus in Franklin.

The announcement comes four months after Milwaukee developer Rick Barrett unveiled plans to build a 44-story apartment and hotel complex two blocks south of the Northwestern Mutual site.

Mayor Barrett told CBS 58's Mike Strehlow he's thrilled with the prospect of another tower rising possibly 30 stories or more nearby.

"They have executives that will stay in the city that will be looking to use the apartments we have, and the hotel, and civic attractions within the Couture. That will be a tremendous complement to what we're trying to do there," Barrett said.

Barrett hopes to break ground on the Coutour in late 2013.

Local elected officials and business leaders will join Northwestern Mutual officials during a news conference Thursday at 11:00 a.m.