Taconic Investment Partners and National Real Estate Advisors are taking a 99-year ground lease on a parking lot and an office tower on West 42nd Street so they can build a 35-story rental tower on the sites.

The parking lot at 311 West 42nd St. and the office building next door are owned by healthcare workers’ union 1199SEIU, Crain’s New York Business reports.

The office building spans 100K SF and is totally occupied by 1199SEIU. The union is moving to a new space at George Comfort & Sons’ 498 Seventh Ave. in a deal that was reached last year.

"It's extremely difficult to find rental residential sites in Manhattan," Taconic Chief Investment Officer Chris Balestra told Crain’s. "This is the type of deal we're always on the lookout for."

The building would also feature 60K SF of retail. Under the terms of the lease, Taconic and its partners will pay monthly rent to 1199SEIU, making building a rental building, rather than a condominium, feasible.

The union will move out in the next two years, according to Crain’s, and the building is slated to be finished in 2022.