Zipf Law (Zipf, 1949) is an empirical evidence which shows a relationship between rank and size of cities. The largest city should be n-times as larger as the nth largest city: the size of each city is measured by its population and the city with largest population has rank 1, and the second rank 2, and so on. This Law has performed surprisingly well for the size distribution of cities in most industrialised countries, although a convincing theoretical framework for its existence is still lacking. Many different analysis has been done in the literature for explaining such an evidence. Generalisations of Krugman (1991 a-b) models -with human capital and congestion- where their outcome are rank-size distributions (as contrary to the original: spreading of identical size cities). This paper focus in the analysis of the rank-size distribution for the Spanish regions since 1960 thru 1998, trying to study the distribution and type of urban agglomeration by regions. Also, the evolution of these agglomerations is contrasted. The paper concludes remarking important differences between the regions and analysing the different patterns of agglomeration of Spanish regions, where Zipf Law is not fulfilled.