Adapazari is a city in northwestern Turkey and the capital of Sakarya Province. The province itself was originally named Adapazari as well. Adapazari is a part of the densely populated region of the country known as the Marmara Region. In 2014, the city had a population of 462,087.

Adapazari is the location of a large automobile factory owned by the Toyota Motor Corporation, as well as the Hyundai EURotem train factory. One of the biggest Turkish defense industry Tank Pallet 1st Main Maintenance of Turkish Defense and Otokar a major manufacturer of buses and military vehicles are located in Sakarya. Other major industries in the city and its surrounding province include textile factories for silk and linen products. Agriculture and forestry also form an important part of the city's economy, with the production of tobacco, hazelnuts (findik variety), walnut-wood, cocoons and vegetables. Adapazari is one of the most important industrial capitals of Turkey. While Turkey is a developing country, the city of Adapazari renovated its infrastructure and industry after the 17 August 1999 catastrophic earthquake which left more than 18,000 casualties behind. In memory of the earthquake municipality had built a museum of earthquake in city center.