At the end of the 18th century, the population of Barcelona stood at just over 100,000 inhabitants; in 1900, the figure had risen to 533,000. Many other cities in Catalonia saw two, three and even fivefold increases in the number of residents during the course of the 19th century. This rise in urban population figures created a large number of problems related to health, sanitation, housing and infrastructure. The old defensive walls were brought tumbling down by the demographic pressure and the new economic and social circumstances.