Somerville’s already gigantic Assembly Row development on the banks of the Mystic could get a mammoth addition. Developer RD Management has filed plans with the state for a 1,941,592-square-foot project covering 9.4 acres of what are mostly now surface parking lots (h/t Bldup.com).

The project—dubbed 5 Middlesex Avenue and the Office and Research Center + the Residences at Assembly—would include 219 apartments or condos (or both) as well as a 188-room hotel and 1,480,000 square feet of office and lab space. All total, the project could include five new buildings, with one 20 stories and two others 19 each.

Everything’s preliminary right now, though the development of Assembly Row has been rather unstoppable. The same goes for its popularity. Stay tuned.