San Lorenzo is a city in the Central Department in Paraguay. It is a suburb of Asunción, and the third most populous city in Paraguay, with a pop…San Lorenzo is a city in the Central Department in Paraguay. It is a suburb of Asunción, and the third most populous city in Paraguay, with a population of 252,561. The National University of Asunción campus is located in San Lorenzo, that's why it is sometimes known as "Ciudad Universitaria". The city is the seat of the Roman Catholic Diocese of San Lorenzo.