I've visited the 9/11 Memorial a couple of times so skipped it on this trip; One World Trade Center (ie Freedom Tower) is still jaw-dropping as the tallest building in the Western Hemisphere (the same architect designed Willis Tower and Burj Khalifa)
Church of the Covenant, an 1867 Gothic Revival masterpiece, has one of the largest collections of liturgical windows by Louis Comfort Tiffany in the country; its 236 foot steeple is the tallest in Boston
There are 5283 points of light in Starlight which graces the rotunda of this former 1932 neo-Georgian home; using state of the art technology, the piece needs minimal energy and generates virtually no heat