Fredrikstad (Norwegian: [ˈfrɛ̀drɪkstɑ] ⓘ; previously Frederiksstad; literally "Fredrik's Town") is a city and municipality in Østfold county, Norway.

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 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.

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.

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.

In 2005, Fredrikstad was the final host port for the Tall Ships' Race, attracting thousands to the city.

[4] After Sarpsborg was burned to the ground during the Northern Seven Years' War, the ruling king, Frederik II, decided by royal decree to rebuild the city 15 kilometres (9 mi) south of the original location.

During the next 60 years, several fortifications at the Fredrikstad Fortress were built, including Isegran, Kongsten, and Cicignon.

In the 1860s, several steam powered saws were built along the river, and in 1879 the railway reached Fredrikstad, leading to further growth.

It later became one of Norway's most important industrial centres, famous for its large shipyard, Fredrikstad Mekaniske Verksted.