 The area was developed mainly in the 1960s and 1970s when immigrant workers, encouraged to move to Barcelona by the government of Francoist Spain, they built housing for themselves.The combination of houses, then isolated on the rural hillside of what is now Parc dels Tres Turons ("Three Hills Park"), ad-hoc buildings put up without building permits and more planned urban development has given the area its modern appearance of many buildings piled on the hillside.Carmel became infamous in 2005 when there was a major tunnel construction accident.