If you have the least bit of historical curiosity, the Vatican is the place to visit.
Just the hall of maps alone is worthwhile. Countless large scale maps of how the landmass of the earth was perceived at the time. These must have been used in sort of a command center for decisions on how Christianity was used to found civilization elsewhere.
From the article, and for the Catholic haters resident here on FR, who are bound to get all stimulated by the conjunction of the terms “Vatican” and “secret” in the same sentence:
“In fact, there is nothing sinister about the title of this treasure trove of historical materials; “secret,” in this case, is Vaticanspeak for the private archives of the papacy, which were opened to qualified scholars in 1881 by Leo XIII, the founder of the modern papacy and a man unafraid of the truths that history could teach.”