Oulu is situated by the Gulf of Bothnia, at the mouth of river Oulujoki, which is an ancient trading site.
The city proper was founded on 8 April 1605 by King Charles IX of Sweden, opposite the fort built on the island of Linnansaari.
This took place after favourable peace settlements with Russia, which removed the threat of attack via the main east-west waterway, the river Oulu.
The surrounding areas were populated much earlier.
Oulu was the capital of the Province of Oulu from 1776 to 2009.

In 1822, a major fire destroyed much of the city.
The architect Carl Ludvig Engel, chiefly known for the neoclassical (empire style) buildings around Helsinki Senate Square, was enlisted to provide the plan for its rebuilding.
With minor changes, this plan remains the basis for the layout of Oulu's town center.
The Oulu Cathedral was built in 1832 to his designs, with the spire being finished in 1844.
During the Crimean War, Oulu's harbour was raided by the British fleet, who destroyed ships and burned tar houses, leading to international criticism.

Once known for wood tar and salmon, Oulu has evolved into a major high-tech centre, particularly in IT and wellness technology.
Other prominent industries include wood refining, chemicals, pharmaceuticals, paper, and steel.

The municipality of Ylikiiminki was merged with the city of Oulu on 1 January 2009.
Oulu and the municipalities of Haukipudas, Kiiminki, Oulunsalo, and Yli-Ii were merged on 1 January 2013.

Oulu was the site of the 2018 Oulu child sexual exploitation scandal.
 Prime Minister Juha Sipilä declared that “Sex crimes against children are inhumane acts of incomprehensible evil.”
Oulu is situated by the Gulf of Bothnia, at the mouth of river Oulujoki, which is an ancient trading site. The city proper was founded on 8 April 1605 by King Charles IX of Sweden, opposite the fort built on the island of Linnansaari. This took place after favourable peace settlements with Russia, which removed the threat of attack via the main east-west waterway, the river Oulu. The surrounding areas were populated much earlier. Oulu was the capital of the Province of Oulu from 1776 to 2009.
In 1822, a major fire destroyed much of the city. The architect Carl Ludvig Engel, chiefly known for the neoclassical (empire style) buildings around Helsinki Senate Square, was enlisted to provide the plan for its rebuilding. With minor changes, this plan remains the basis for the layout of Oulu's town center. The Oulu Cathedral was built in 1832 to his designs, with the spire being finished in 1844. During the Crimean War, Oulu's harbour was raided by the British fleet, who destroyed ships and burned tar houses, leading to international criticism.
Once known for wood tar and salmon, Oulu has evolved into a major high-tech centre, particularly in IT and wellness technology. Other prominent industries include wood refining, chemicals, pharmaceuticals, paper, and steel.
The municipality of Ylikiiminki was merged with the city of Oulu on 1 January 2009. Oulu and the municipalities of Haukipudas, Kiiminki, Oulunsalo, and Yli-Ii were merged on 1 January 2013.
Oulu was the site of the 2018 Oulu child sexual exploitation scandal.  Prime Minister Juha Sipilä declared that “Sex crimes against children are inhumane acts of incomprehensible evil.”
Oulu