‚zmit is an important industrial centre, with a large oil refinery, and major paper and cement industries. Ford Motor Company has a plant here in a joint venture with Otosan, assembling the Transit/Tourneo and Transit/Tourneo Connect vans. It is also a transportation hub, being located on the main road and rail lines between ‚stanbul and Ankara, and having a major Port.
There is also tourism in the city and its region. There is a 16th-century mosque by Sinan. There are remains of the ancient walls and a Byzantine fortress. The thermal spa at nearby Yalova is well-known.
In antiquity, the city was called Astacus or Olbia. After being destroyed it was rebuilt in 264 BC as Nicomedia, and it became the capital of the eastern Roman Empire until the founding of Constantinople.
Constantine the Great died at a royal villa nearby. Hannibal committed suicide in a castle nearby. The historian Arrian was born there.
The earthquake of August 17, 1999 (magnitude 7.4) devastated the region, killing more than 14,000.