 The south and east sides of Great Blue Hill drain into the Blue Hill River, thence into the Farm River, Monatiquot River, Weymouth Fore River, and into Boston Harbor.Its summit is the highest point in Greater Boston and Norfolk County and also the highest within 10 miles of the Atlantic coast south of central Maine.For this reason, American meteorologist Abbott Lawrence Rotch chose Great Blue Hill as the site for an observatory, which became known as the Blue Hill Meteorological Observatory after its completion in 1885.