Kocaeli is one of Turkey’s ten largest cities, located in the Marmara Region and known for its industry. Its historical roots date back to ancient Bithynia, and it was an important center during the Roman and Ottoman periods. Thanks to its proximity to İstanbul and developed transportation network, it is the heart of industry and commerce. Kocaeli also draws attention with its natural beauty, including the Samanlı Dağları and İzmit Körfezi. The city offers visitors a variety of experiences with both its historical richness and modern lifestyle.Wikipedia