The so-called "Sack of Palermo" was one of the dramatic consequences of this problem. The term is used to indicate the speculative building practices that resulted in the destruction of a great number of historical buildings and green areas, filling the city with poor buildings, mainly between the 1950s and the 1980s. The reduced importance of agriculture in the Sicilian economy has led to a massive migration to the cities, especially Palermo, which swelled in size, leading to rapid expansion towards the north. The regulatory plans for expansion was largely ignored in the boom. New parts of town appeared almost out of nowhere, but without parks, schools, public buildings, proper roads and the other amenities that characterise a modern city.