From the History of Easton, Mass., by W. L. Chaffin, 1886, pp. 687-688
"This Hall was built in memory of Oakes Ames by his children, and was presented by them to the town. It stands on the solid foundation of a natural ledge, from the northeast corner of which rises the beautiful octagonal tower, on whose frieze are carved the twelve signs of the zodiac. For the entire length in front the building is ornamented with an arcade having five arches, which rest upon low strong columns with carved capitals. The material used in the construction of the first story of this building is the sienite stone from a quarry only a few rods distant, the second story being finished in handsome brick; the trimmings are of red sandstone, and the steep imposing roof is covered with red tiles. Over the front dormer window appears a monogram formed of the letters O. A. The Hall stands at a high elevation above the road, though near to it, and is approached by wide stone staircases, terminating on stone platforms, and so combined with the natural stone-work as to present a grand appearance. On the first floor of the building are two small halls; on the second floor is the main hall, which, exclusive of a large stage, is fifty-nine feet in length, forty-seven in width, and twenty in height, - the stage measuring twenty-six by eighteen feet. The upper room is beautifully finished as a Masonic Hall. The whole building outside, excluding the tower, is ninety-six and one third feet in length. The architect of this noble building was H. H. Richardson.
Memorial Hall was dedicated November 17, 1881, with interesting exercises; and on that occasion it was formally presented by Oliver Ames to the chairman of the Board of Trustees, who were to hold and manage the building for the benefit of the town of Easton."
Here are some more recent photos of Oakes Ames Memorial hall: