Guimarães is considered the birthplace of Portugal because Afonso Henriques, who went on to be the first king of Portugal, was born here.
The historical centre in the area that was within the Guimarães city walls, is associated with the formation and identity of Portugal, and was classified a World Heritage site based on the originality and authenticity applied in its restoration. The city still has a harmonious, well-preserved heritage that is evident in the graceful iron verandas, granite balconies and porticos, mansions, arches connecting the narrow streets, paving slabs smoothed by time, towers and cloisters. For a moment you might imagine yourself to be in a mediaeval setting, where the nobility built their houses over time, such as the Mota Prego house, the Vila Flor and Toural palaces, and the many others that give Guimarães its unique atmosphere.
Source reference: Visit Portugal