[5] The capital of Kocaeli Province, it is located at the Gulf of İzmit in the Sea of Marmara, about 100 km (62 mi) east of Istanbul, on the northwestern part of Anatolia.

Following Constantine the Great's victory over co-emperor Licinius at the Battle of Chrysopolis in 324, Nicomedia served as an interim capital city for Constantine between 324 and 330, when he rebuilt and expanded the nearby city of Byzantium as the new Roman capital; formally dedicating it in 330 with the name Nova Roma,[7] before he soon renamed it as Constantinopolis (modern Istanbul).

The city is mostly built on hill slopes because of the cramped area, while flat plains surround the gulf, near the sea.

Carthaginian general and statesman Hannibal came to Nicomedia in his final years and committed suicide in nearby Libyssa (modern Gebze), in a date between 183 and 181 BC.

Nicomedia remained as the eastern (and most senior) capital of the Roman Empire until Licinius was defeated by Constantine the Great in 324.

Constantine mainly resided in Nicomedia as his interim capital city for the next six years; until in 330 he declared the nearby Byzantium as Nova Roma, which eventually became known as Constantinople (modern Istanbul).

Owing to its position at the convergence of the Asiatic roads leading to the new capital, Nicomedia retained its importance even after the foundation of Constantinople.

After the sack of Constantinople in 1204, during the Fourth Crusade, the city of Nicomedia, with most of the Bithynia province, became a part of the Latin Empire.

An Allied report (on 1 June 1921) stated that a large number of excesses were committed by both sides during the last year, while the Turkish atrocities in the Izmit peninsula "have been more considerable and ferocious than those on the part of the Greeks".

Ford Motor Company has a plant here in a joint venture with Otosan, assembling the Transit/Tourneo (including the new V362 Transit/Tourneo Custom since late 2012) and Transit/Tourneo Connect vans.

In the past few years the province has developed into a growth point for the Turkish automotive industry, receiving investments from Ford, Hyundai, Honda and Isuzu.

Financial Times affiliated Foreign Direct Investment magazine nominated Kocaeli (the province of which İzmit is the capital) among the 25 European Regions of the Future for 2006–2007.

There are 102 neighbourhoods in İzmit District:[18] Located along the commercially-active Black Sea and Marmara Sea shorelines, Kocaeli boasts 5 ports and 35 industrial docks, making it an important communications center, as well as Anatolia's farthest inland contact point and a gateway to global markets.

The main transportation routes, the D100 highway and the Trans European Motorway which connects Europe with Asia, along with railway lines, form an intercontinental passage network.

On 1 March 1958, SS Üsküdar, a small passenger ferry sailing between İzmit and Değirmendere sank due to lodos weather.

It has established a department of international relations that monitors Bologna developments closely and oversees KOU's participation in the Erasmus and Leonardo da Vinci student mobility schemes.

With membership in the European University Association, KOU is aiming for greater international recognition of its academic work.

The university, while focusing on technical and engineering subjects, offers an extensive selection of courses in social sciences and arts as well.

Precipitation is high and fairly evenly distributed the year round; it is heaviest in late fall and winter.