Massachusetts General Hospital is pushing ahead with a $1.9 billion addition to its Boston campus.

A pair of mid-rise towers along a corner of its Boston campus on Cambridge Street would add more than a million square feet to its Boston campus. A joint venture between Turner Construction Co. and Walsh Brothers Inc. will build the project, with the architectural and planning firm NBBJ handling the design.

The hospital and its project team hope to start construction next year, having first broached the proposal back in 2019.

"We have been working diligently on advancing this project," said Nick Haney, a project manager for MGH, at a recent public meeting.

The Boston Planning and Development Agency is now gathering comments from the public on the massive MGH project and its design, with the project’s height and other features likely evolving before the final plan is approved.

The project itself involves the construction of more than a million square feet of new space on roughly five acres, with MGH planning to move its cancer and cardiovascular service into the new complex, which will also have hundreds of beds as well. The total net gain, however, for the hospital will only be in the range of 94, as beds in older parts of MGH are decommissioned, according to plans the hospital has filed with city development officials.

By moving cardiac and cancer services to a single location, MGH said it hopes to spur collaboration between the key medical fields, while also boosting potential multidisciplinary research as well.

However, before anything can get built, demolition crews will have to take down a number of aging, older buildings dating from late 1800s and early 1900s on the site totaling three hundred thousand square feet.

The project will also include some historic preservation, with plans to incorporate the street-facing facades of the former Winchell School, which dates to the 1880s, into the northeast corner of the new building at Blossom and Parkman streets.

The new complex will also include 977 parking spaces, with six below-grade stories, as well as a new bicycle storage area.

MGH estimates the project will take seven years to build, with the eastern portion of the building coming online in 2026, follow by the western portion in 2029.