Monaco, officially the Principality of Monaco, is a sovereign city-state and microstate on the French Riviera in Western Europe. It is bordered by France to the north, east, west and by the Mediterranean Sea to the south. With an area of 2.1 km2 (0.81 sq mi), it is the second smallest sovereign state in the world, after Vatican City. Its 19,009 inhabitants per square kilometre (49,230/sq mi) make it the most densely-populated sovereign state in the world.

Vatican City, officially the Vatican City State, is the Holy See's independent city state, an enclave within Rome, Italy. The Vatican City State, also known as The Vatican, became independent from Italy with the Lateran Treaty (1929). With an area of 49 (121 acres) and a population of about 825, it is the smallest sovereign state in the world by both area and population.