Helsingborg, formerly Hälsingborg, city and seaport in southern Sweden, on a strait called the Öresund, in Skåne County. Helsingborg is situated opposite Helsingør, Denmark, with which it is connected by railway ferry. The modern city was established in the early 15th century near the site of the old town, which was known as a trade center as early as the 9th century. A ruined fortress is all that remains of the old town. The city belonged to Denmark until 1658, when it was ceded to Sweden. The Danes recaptured it several times, however, and it did not come under permanent Swedish control until 1710. Helsingborg is an important port and one of the leading manufacturing centers in the country. It is located near the only coalfield in Sweden and near large clay deposits. Among the principal industrial establishments in Helsingborg are sugar and copper refineries, breweries, superphosphate works, potteries, and rubber factories. Population (1998 estimate) 116,337.