The Sack of Baghdad was one of History's greatest atrocities. While I'm always perfectly fine with murdering my family and sending thousands of soldiers to their deaths to fulfill my greed for land, I always feel a bit guilty when the messages of "you have taken city X, burning all its libraries and destroying all its monuments and artifacts and causing a destruction of knowledge that shall resound for thousands of years" pop up while playing as the Mongols, recreating that crime through all the famed cities of Europe. Maybe we should have an option to spare those cities, losing prestige (cause you are a Mongol, you're supposed to be into that whole "rape and pillage and burn" shtick) but gaining a tech boost?