Conflicting Histories

You arrive at the address that the strange note had detailed: 66 Avenue Street, City. You read the note again to ease your doubts: “Historian, we need your expertise. Come to the Museum at 66 Avenue Street at 5:30 tonight, come alone. Look at this drawing of the cache aid, find it, and help recover what has been stolen.”
The museum looks about two hundred years out of date to the rest of its urban surroundings. The Greco-Roman inspired structure is worn and deserted, with only a frayed banner stating THE LIFE OF JOHN FITZGERALD KENNEDY flapping above the front door. Wondering how on earth you thought this was a good idea, you walk through the revolving door...