Owing to the predominance of volcanic cones and craters in the interior, human settlement has developed primarily along coastal and interior plains. In addition, there are several communities that have developed within ancient craters (such as Sete Cidades, Furnas or Povoação), river-valleys (such as Ribeira Chã, Pilar da Bretanha) or coastal deltas (Mosteiros). Regardless, these settlements were largely agrarian and concentrated around the parish churches and the many fertile parcels of land. The communities were largely isolated throughout the year, owing to the great distances and rough landscape of the island, and only became integrated with the development of the many road networks that circle and bisect the island. Two cities have developed, largely because the island was divided by mountainous volcanic cones in the interior: Ponta Delgada and Ribeira Grande. Administratively, the island is governed by five municipalities, with Ponta Delgada and Ribeira Grande having more administrative functions associated with their larger populations: