The exterior of the Old South Church in Boston (built in 1874) is made out of Roxbury conglomerate, or puddingstone; photo by Wally Gobetz on Flickr (noncommercial use permitted with attribution / no derivative works).
Official State Rock of Massachusetts
Massachusetts designated Roxbury Puddingstone (also called Roxbury conglomerate) as the official state rock in 1983. All State Rocks
Massachusetts also recognizes an official building stone (granite), a glacial rock (rolling rock), an explorer rock (Dighton rock), a historical rock (Plymouth rock), a state mineral (babingtonite), and a state gem (rhodonite).