The increase in agricultural production and the development of trade stimulated demographic and economic growth in the principality. The cities, manufacturing and trade centres, were particularly dynamic and fought to achieve or increase their levels of self-government. The cities were helped by the monarchs, who, in their turn, were looking for firm support against a nobility whose loyalty was uncertain.

Urban growth became unstoppable, as testified by the number of public, religious and private buildings constructed at this time in the new and clearly urban Gothic style. In Barcelona, Mallorca, Perpinyà (Perpignan) and Valencia, new and spectacular churches, cathedrals, commodity exchanges and palaces rose up, the symbols of an expansion which, driven by the cities, triumphed all around the Mediterranean.