Portugal's second-largest city with around 216,000 inhabitants in the north of the country on the Atlantic coast near the mouth of the Douro River. In England, the city was called "Oporto" in the 17th and 18th centuries because it is customary in the Portuguese language to prefix the city name with the (masculine) article "o" (o Porto). Therefore, it was mistakenly assumed that the city was called "Oporto". The famous port wine is thus named after the port from where it was exclusively finished and shipped for a long time, and not after the region of origin or the DOC area Douro (full name is Porto e Douro). Porto has been an important trading centre with long-established merchants since the Middle Ages. The famous Factory House, built in 1790 by British port wine merchants, still serves as a gentlemen's club and meeting place for the remaining British merchant houses.