The Monument John Quincy Adams was looking at as he wrote in his diary on September 20, 1824. I finally found it.

I was always facinated by J.Q. Adams passage in his diary of Sept. 20, 1824. When wrote of his fathers granite markers to his grandparents and great grandparents. He wrote down all that it said on the markers. He also mused who would of posterty come and visit this and the three at that time Generations now living. So it was with pleasure that I with my ledger (diary) in hand, wrote in the same spot and answered his question posed nearly 182 years earlier. History does not get much better than that! I am hoping to return to Quincy this year and do more research so I can write more on the lives and work of the Adams family.