Surface Area and Population Density
There are only .44 square kilometers of area within the Vatican City, so the entire population is contained within less than a single square kilometer of space.
Demographics in the Vatican City
Italian, Swiss, Argentinian, and other nationalities are common among the population that resides here. The languages include Italian, Latin, French, and various other languages as pertaining to the current residents. The residents are those that work in the city itself and in some cases their family members. Papal approval is required to become a citizen of the Vatican City.
11 February 1929 is the date that the three treaties were signed - giving full sovereignty of the land to the Vatican City and allowing it to establish it's own absolute monarchy. Currently, Pope Francis holds the chief of state position in the Holy See (as it is otherwise known).