The owner of a downtown Minneapolis building that TCF Bank recently vacated is planning to demolish the structure and replace it with what could be the city's tallest new skyscraper in more than 20 years.

Plans for the 50-story tower include a full-service hotel, apartments and office space. Massachusetts real estate investment firm Franklin Street Properties Corp., which revealed the outlines of its plan Tuesday, said work could start in the second half of 2016.

The current, four-story structure at 801 Marquette Av., called TCF Bank Building, was abandoned by its anchor and namesake tenant when the bank moved more than 1,100 employees from downtown to a Plymouth office building.

Franklin Street said it has yet to reach a final development agreement, but in 2014 it announced a redevelopment team for the property that includes Minneapolis-based developer and builder Ryan Cos., architectural firm Perkins+Will and leasing agency CBRE Group.

At that time, a vice president with the firm said in a statement that it was "an opportune time for optimizing the potential of the location" and that Franklin Street "saw significant untapped potential on the site" when it bought the building.

The company did not return a request for comment Tuesday.

The four-story TCF Bank Building at 801 Marquette would give way to a hotel-office-apartment tower.

Franklin Street said Tuesday that it will contribute about $80 million to $90 million and the land itself to the new tower project.

It plans to maintain ownership of the office portion of the project — about 260,000 square feet — when it's complete.

Early plans suggest the three different uses would be stacked on top of one another, with the hotel on the bottom, offices in the middle and apartments on the highest floors.

The precise height of the 50-story structure is unknown, so it's not clear where it would rank among the city's towers. Office floors are typically taller than apartment or hotel units, and the ratio of hotel, office and apartment floors has not been disclosed.

The tallest buildings in the city — the IDS and Capella towers and the Wells Fargo Center — all surpass 55 floors. But construction over the past two decades hasn't approached that.

The city's most recent high-rise, LPM Apartments, is 36 stories.

The last office towers to go up downtown, in 2001, were the 33-story Target Plaza South and the 30-story 50 South Sixth towers.

With its mix of uses, the Franklin Street project could also be a first of its kind for Minneapolis.

"I don't know that we've ever had all three uses attempted in a single tower in this market," said Russ Nelson, president of NTH, a Minneapolis-based real estate and project management firm.

"There's much more complexity brought with the different project aspects, but someone has to try and figure it out."

In addition to the four-story building, which dates to 1931, Franklin Street owns the adjacent 17-story tower, also still bearing the bank's name, TCF Tower.

"Significant thought and design are being incorporated into the redevelopment of 801 Marquette Avenue in order to integrate it with and enhance the appeal of its next-door neighbor office building," Franklin Street said Tuesday in an earnings report in which it discussed its plans for the site.

The proposed tower's location was once the hottest block in town.

The Foshay Tower, which is connected to the current TCF Bank Building, soared far above all others for decades after its construction in 1929. In 1972, the IDS Center — which is kitty-corner from Franklin Street's site — was built, dwarfing the Foshay.

Franklin Street Properties started batting around redevelopment ideas more than a year ago after TCF announced its departure.

Rather than viewing it as a fatal blow, the owner saw the change as the right moment to redevelop and try to improve the site's value.

With TCF's lease expiring at the end of this year, there are fewer tenants to displace with construction.

With construction now targeted for next year, the development team would likely bring its proposal to the city for approvals as early as January.

Kristen Leigh Painter • 612-673-4767