The correct answer is - Monaco.
The most densely populated country in Europe is the country of Monaco. It is a very small country between France and Italy, and it is also a very rich country. Monaco is a place where lots of rich people decide to leave because it is an elite mini country that has a lot to offer, so the amount of people on such a small area makes it very densely populated, more specifically, 15,323 people per square kilometer.
The countries that follow by population density in Europe are Vatican, Malta, and San Marino. What is noticeable is that the most densely populated countries in Europe are actually the smallest countries on the continent, that also have a very high income per capita.