Halden, formerly Fredrikshald, is a town and municipality in the county of Østfold, Norway. It had 27,204 inhabitants as of January 1, 2002.
Due to its location at the Swedish border, the fortress Fredriksten was built there in the 17th century. The fortress was a replacement for the former border fortress Bohus which had been lost at the Treaty of Roskilde in 1658, when the province of Wiken, or Bahusia, was ceded to Sweden.