Downtown Milwaukee's BMO Harris Bank building has been sold to a developer, setting the stage for construction to begin this year on a new office tower for the bank and other businesses.

The Irgens development firm has closed on its acquisition of the 20-story office building, 770 N. Water St., its adjacent seven-level parking structure and an adjoining parking lot, developer Mark Irgens said Tuesday.

He declined to disclose financial terms, which includes BMO Harris leasing back the space from Irgens.

Irgens and BMO Harris in December announced plans for the 25-story BMO Harris Financial Center, which the development firm will build on a parcel now occupied by the parking structure. That site is south of E. Wells St. between N. Water St. and N. Broadway.

Work to relocate utilities at the development site begins this month, followed by the parking structure's demolition.

The 379,400-square-foot BMO Harris Financial Center and its 647-stall parking ramp are to be completed in December 2019.

The office tower will be anchored by the 124,000-square-foot Wisconsin headquarters for BMO Harris, and the Michael Best & Friedrich LLP law firm, leasing 60,000 square feet. The law firm will move from the 100 East office tower, 100 E. Wisconsin Ave.

The project will include a BMO Harris retail bank at N. Water and E. Wells streets that will be integrated into a 30-foot-high main lobby.

There will be 12,000 square feet of additional retail space. Irgens is in discussions with an unnamed high-end restaurant group for two restaurants in that space. There also is leasing activity in the remaining office space.

After BMO Harris moves to its new offices, Irgens in 2020 will begin converting the existing 20-story building at 770 N. Water St. into a mixed-use development. The firm is considering such uses as a hotel, offices and housing.

“The overall project brings in excess of $175 million in new construction and redevelopment to Milwaukee while securing the continued commitment of great companies like BMO Harris Bank and Michael Best to our community," Irgens said in a statement. "We are pleased to further our pledge of contributing to Wisconsin’s economic development through our investors and our local design and construction teams."

“The BMO Harris Financial Center signals our commitment to Milwaukee, and to the economic development of the region,” said David Casper, BMO Harris president and chief executive officer. “We’re excited for this project to begin, and we’re pleased to work with Irgens on the development of a truly transformational new office tower.”

The contractor on the building project is JH Findorff & Son, and the architect is Kahler Slater.

Brokers Dan Jessup and Steve Steinmeyer, of Jones Lang LaSalle, represented Michael Best & Friedrich. Scott Welsh and Lyle Landowski, of Colliers, and Jessup and Jeff Liljeberg, of Jones Lang LaSalle, represented BMO Harris.

Tom Daykin can be reached attdaykin@jrn.com