This paper focuses on the influence of two classical engines of population agglomeration: geography versus history. Geography is identified by two co-ordinates: coastal position and altitude. The prominence of history is captured also by two characteristics: the initial size of the municipalities, and the condition of being the administrative centre of the area. Our reference is census population data for Spanish municipalities for period 1900-2001. The eleven censuses have been homogenised according to the municipal structure of 2001 Census.