SL Green and Japan’s Mori Building Co. have announced a joint-venture partnership to develop a new Madison Avenue office tower. The 46-story project is already underway, with the demolition of the old Brooks Brothers building at 346 Madison Ave. and the neighboring 11 E. 44th St. set to begin in the third quarter of this year, according to SL Green leasing director Steven Durels.

The 850,000 square-foot tower is expected to be completed by the third quarter of 2031, making it one of the most highly amenitized new buildings in the city. Features will include nine floors with terraces, nine with loggias, a luxury wellness center, a 215-seat auditorium, indoor padel court, and a landscaped terrace overlooking the avenue. The tower will be designed by KPF, although renderings have not been released yet.

Renowned chef Daniel Boulud will operate an Epicerie fast-casual food spot in a tenants’ lounge, with plans for a world-class restaurant on the ground floor. The project is part of a wave of major office developments and redevelopments on Madison Avenue in the East 40s, including BXP’s 343 Madison and JP Morgan Chase’s redesign of 383 Madison.

SL Green chairman Marc Holliday announced that the company will sell a 49 percent stake in the project to Mori, Japan’s largest urban landscape developer, with SL Green managing development and leasing.

Durels highlighted the proximity to One Vanderbilt and the new JP Morgan Chase headquarters as key drivers of the Madison corridor boom, following the success of One Vanderbilt in transforming the west side of Grand Central into a luxury location.