Mayor Marty Walsh is expected on April 10 to introduce legislation that would lead to the construction of Boston’s tallest residential tower on the site of the city-owned Winthrop Square Garage.

Millennium Partners, the same folks behind current-tallest-residential building Millennium Tower in Downtown Crossing, want to build to 750 feet in place of the garage at 240 Devonshire Street in the Financial District.

The development firm is willing to pay the city $153 million for the honor.

But current laws forbidding certain amounts of shadow on Boston Common and the Public Garden at certain times preclude the construction of such a tall tower.

Walsh’s proposed legislation would exempt Millennium Partners’ Winthrop Square Garage plans, but ban future projects from casting such shadows.

Per the Globe’s Tim Logan, it would also toughen rules governing shadows from new construction on Copley Square and require a new zoning plan for development in Downtown Crossing and the Financial District.

Walsh’s idea needs not only City Council approval, but green lights from the state Legislature and Gov. Charlie Baker as well.

Meanwhile, Millennium Partners has said it has no intention of chopping the height of its proposed tower.

Stay tuned.