Millennium Partners is proposing 900,000 square feet of office and research space in one of the “signature redevelopment parcels” within South Boston’s Raymond L. Flynn Marine Park.

Parcels T and T-1 are occupied by a vacant warehouse and surface parking, which would be redeveloped as a mixed-use project including retail and restaurant uses, developer Jacob Citrin wrote in a notification letter to the Boston Planning and Development Agency.

Parcel T, known as the Boston Freight Terminal, spans 3 acres and contains a nearly 136,000-square-foot warehouse.

Parcel T-1 at the corner of Northern Avenue and Channel Street is outside the Chapter 91 boundary, which limits development to marine industrial and related use. The parcel totals 1.6 acres and sits above the Ted Williams Tunnel.

The project will include retail and restaurant space, according to a notification letter by Jacob Citrin on behalf of Millennium Partners.

Parcel T was identified as a potential “signature redevelopment parcel” in the Boston Planning and Development Agency’s 2017 marine park master plan, because of its size and more flexible zoning than other properties in the marine park.

Millennium’s efforts to develop the parcels were linked to its proposal to build a gondola along Seaport Boulevard connecting them to South Station. The proposal stalled after attracting significant public criticism and after Millennium was unable to reach a deal with a potential anchor tenant in a development that would have been fed by the gondola.