We've known for a while that Boston Properties, the developer behind innumerable properties and projects, including those ginormous TD Garden towers, wanted to build a big complex above Back Bay Station, using air rights from the state gained in part by a commitment to sprucing up the transit hub. The developer just filed plans with the city that further clarify its proposal. Specifically, Boston Properties wants to construct a 1.4 million-square-foot complex of offices, residences and retail above the T stop and a neighboring parking garage it owns at 165 Dartmouth Street. As the Globe's Tim Logan notes, "any development of that size would mark the city's skyline alongside the John Hancock Tower, Prudential Center, and a new generation of towers that have been proposed but not yet built."

There's one thing we don't know, though, even with the fresh filing: the proposed complex's height. Might it rival recent arrivals such as the 60-story Millennium Tower in Downtown Crossing? Or soon-to-be spires such as the 61-story One Dalton, also in Back Bay? We'll see what happens. It's early days with this one, and building in Back is usually a tricky affair. Expect delays.

· New Complex Proposed Over Back Bay Station [Globe]

· Back Bay Station Redo Could Come w/ Skyscraper on Top [Curbed Boston]

· Ginormous Project Next to TD Garden Could Start This Year [Curbed Boston]

· One Dalton Developer Expects Most Buyers Will Be Local [Curbed Boston]

· Millennium Tower's Crane Now Boston's Tallest Structure Ever [Curbed Boston]

· Giant Copley Place Tower Almost There [Curbed Boston]