Porto is a Portuguese city on the Atlantic Ocean in the northern part of the country. The waterfront called Cais da Ribeira is a popular place for walks among the inhabitants of Porto, as well as tourists. Ribeira is a historical district of the city, designated World Heritage by UNESCO. Formerly it was inhabited the workers and the urban poor, today Ribeira attracts visitors with cramped streets and narrow, historic buildings with colorful facades, which rise above the river Douro. The oldest buildings of the city are situated in this part of Porto. The district of Ribeira can be admired from the famous Dom Luis I Bridge.