Most Visited City in Every Country

The research for this quiz took me very long, it was no simple Wikipedia search. In my search, there were many confounding sources especially with the less travelled countries, for these situations I tried using the most official sources (i.e. govt. sources). Another consideration was domestic travel, for a country like the United States it seems like an obvious inclusion but, for San Marino it's a different story. Because of this type of discrepancy I stuck to only include international travel. For some countries there was only information on airport arrivals, and/or Hotel nights booked, so this information was used. For about dozen entries there was no travel numbers, and no obvious most visited city, for these, I researched the most promoted city to visit, and also considered airport/hotel locations, population, and means of transport. By no way was this an exact science. I welcome any differing sources in order to perfect this quiz. Thank You.