total population of 3,241,003. Thus, these departments and the eastern portion of San José, which together constituted the Greater Montevideo region, held over one-half of Uruguay's population. This monocephalic pattern of settlement was more pronounced in Uruguay than in any other nation of the world, barring city-states. The 1985 census indicated a population density of about 2,475 inhabitants per square kilometer in the department of Montevideo and about 80 inhabitants per square kilometer in the department of Canelones. Densities elsewhere in the country were dramatically lower. Montevideo was founded on a promontory beside a large bay that forms a perfect natural harbor. In the 19th century, the British promoted it as a rival port to Buenos Aires. The city has expanded to such an extent that by 1990 it covered most of the department. The original area of settlement, known as the Old City, lies adjacent to the port, but the central business district and the middle-class residential areas have moved eastward. The only exception to this pattern of eastward expansion is that banking and finance continued to cluster in the Old City around the Stock Exchange, the Bank of Uruguay (Banco de la República Oriental del Uruguay—BROU), and the Central Bank of Uruguay. Since the 1950s, Montevideo's prosperous middle classes have tended to abandon the formerly fashionable downtown areas for the more modern high-rise apartment buildings of Pocitos, a beachfront neighborhood east of the center. Still farther east lies the expensive area of Carrasco, a zone of modern luxury villas that has come to replace the old neighborhood of El Prado in the north of the city as home to the country's wealthy elite. Its beaches were less polluted than those closer to the center. Montevideo's Carrasco International Airport is located nearby, crossing the border to Canelones Department. The capital's principal artery, 18 July Avenue, was long the principal shopping street of Montevideo, but it has been hurt since the mid-1980s by the construction of a modern shopping mall strategically located between Pocitos and Carrasco. Montevideo's poorer neighborhoods tended to be located in the north of the city and around the bay in the areas of industrial activity. However, the degree of spatial separation of social classes was moderate by the standards of other cities in South America. Starting in the 1970s, the city began to acquire a belt of shantytowns around its outskirts, but in 1990 these remained