Mass. Gen. Laws ch. 92 § 95
The commission may grant permits, upon such terms and conditions as it deems proper, for the projection of eaves, cornices or ornaments of buildings, beyond the line of restriction or setback established for the benefit of the commonwealth, upon the land of a private owner which abuts on lands under the control of the commission, and also for the projection of eaves, cornices or ornaments of buildings over land under the control of the commission; provided, that no grant hereunder shall be made for any projection of more than three feet, nor for a projection over land of the commonwealth held or in the opinion of the commission likely to be required for a boulevard or driveway, at a height less than thirty feet above the grade which the commission may determine as that established or likely to be established as the grade of such boulevard or driveway adjacent to said private land.
Mass. Gen. Laws ch. 92, § 95