Las Siete Calles or Casco Viejo in Spanish or Zazpikaleak or Alde Zaharra in Basque are different names for the medieval neighbourhood of Bilbao, part of the Ibaiondo district. The names mean Seven Streets or Old Town respectively and it used to be the walled part of the town until the end of the 19th century.
Read more about Casco Viejo: The Seven Streets, Tourism