National roads are seen with pentagonal black-on-white shields with a number. National primary routes are divided into two types: the main routes, which connect at least three cities with a population of at least 100,000 people. they are numbered from N1 to N49. The other primary routes connect at least two major cities or towns, numbered N50 to N99. National secondary routes are numbered N100 to N999. National tertiary routes do not have any route numbers at all, as they are highways the provide access to small areas.