Question: The Fisher Hill Reservoir and Gatehouse are a historic element of the public water supply for which metropolitan region of New England encompassing the municipality of Boston, the capital of the US state of Massachusetts, and the most populous city in New England, as well as its surrounding areas? 
Sentence (from "Greater Boston"): The region forms the northern arc of the US northeast megalopolis and as such, Greater Boston can be described as either a metropolitan statistical area (MSA), or as a broader combined statistical area (CSA).
Relevant evidence: No