Fredrikstad (Norwegian: [ˈfrɛ̀drɪkstɑ] ; previously Frederiksstad; literally "Fredrik's Town") is a city and municipality in Østfold county, Norway. The administrative centre of the municipality is the city of Fredrikstad.
The city of Fredrikstad was founded in 1567 by King Frederick II, and established as a municipality on 1 January 1838 (see formannskapsdistrikt). The rural municipality of Glemmen was merged with Fredrikstad on 1 January 1964. The rural municipalities of Borge, Onsøy, Kråkerøy, and Rolvsøy were merged with Fredrikstad on 1 January 1994.
The city straddles the river Glomma where it meets the Skagerrak, about 20 kilometres (12 mi) from the Sweden border. Along with neighboring Sarpsborg, Fredrikstad forms the fifth largest city in Norway: Fredrikstad/Sarpsborg. As of 30 September 2021, according to Statistics Norway, these two municipalities have a total population of 141,708 with 83,761 in Fredrikstad and 57,947 in Sarpsborg.
Fredrikstad was built at the mouth of Glomma as a replacement after Sarpsborg (15 kilometres (9 miles) upstream) was burnt down by the Swedish Army in the 1500s. Some of the citizens stayed behind and rebuilt their old town at its original site and got their city status back in 1839.
The city centre is on the west bank of the Glomma, while the old town on the east bank is Northern Europe's best preserved fortified town.
Fredrikstad used to have a large sawmill industry and was an important harbour for timber export, then later on shipbuilding, until the main yard was closed in 1988. The main industries are currently various chemical plants and other light industry.
In 2005, Fredrikstad was the final host port for the Tall Ships' Race, attracting thousands to the city. In 2019, it was the first host port.
In 2017, Fredrikstad won the national award for most attractive city. The award is given yearly by the Norwegian government on the basis of social, economic and environmental factors.