Şehit Polis Recep Topaloğlu Sports Hall

Kocaeli B.B. Ice Arena (Turkish: Kocaeli B.B. Olimpik Buz Sporları Salonu), formerly Kocaeli Ice Rink, is an indoor ice skating and ice hockey arena located at Şirintepe neighborhood of Izmit in Kocaeli Province, Turkey. It was opened in 1999 and has a seating capacity of 3,600 spectators.It was built according to International Ice Hockey Federation specifications, which are given in metric units (the Imperial units given are approximations): 61 m × 30 m (200 ft × 98 ft) with a corner radius of 8.5 m (28 ft). The arena is home to Kocaeli B.B. Kağıt Ice Hockey Men's team, which plays in the Turkish Ice Hockey Super League. Turkish Ice Hockey Women's League matches are also played in the arena, which hosts the women's ice hockey team of the same club.

Köseköy railway station (Turkish: Köseköy istasyonu) is a railway station in Kartepe, Turkey, in the İzmit metropolitan area. TCDD Taşımacılık operates four daily regional trains between Istanbul and Adapazarı that stop at the station. The station was originally built in 1975 by the Turkish State Railways, when the Istanbul-Ankara railway was realigned to bypass İzmit's city center. The Köseköy Logistics Center is located adjacent to the station and is an important freight yard on the railway.Köseköy station was closed down on 1 February 2012 due to construction of the Ankara-Istanbul high-speed railway. The station was reopened in 2018.

Kırkikievler railway station (Turkish: Kırkikievler istasyonu) was a railway station in İzmit, Turkey. It was serviced by the Adapazarı Express regional train service from Istanbul to Adapazarı. Located just south of the city center, the station was originally built in 1975 by the Turkish State Railways, when the Istanbul-Ankara railway was realigned to bypass İzmit's city center.Kırkikievler station was closed down on 1 February 2012 due to construction of the Ankara-Istanbul high-speed railway.

Kartepe is a municipality and district of Kocaeli Province, Turkey. Its area is 301 km2, and its population is 136,625 (2022). The mayor is Mustafa Kocaman (AKP).

İzmit (Turkish pronunciation: [ˈizmit]) is a municipality and the capital district of Kocaeli Province, Turkey. Its area is 480 km2, and its population is 376,056 (2022). 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. Kocaeli Province (including rural areas) had a population of 2,079,072 inhabitants in 2022, of whom approximately 1.2 million lived in the largely urban İzmit City metro area made up of Kartepe, Başiskele, Körfez, Gölcük, Derince and Sapanca (in Sakarya Province). Unlike other provinces in Turkey, apart from Istanbul, the whole province is included within the municipality of the metropolitan center. İzmit was known as Nicomedia (Greek: Νικομήδεια) and Ólbia (Greek: Ὀλβία) in antiquity, and was the eastern and most senior capital city of the Roman Empire between 286 and 324, during the Tetrarchy introduced by Diocletian. 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, before he soon renamed it as Constantinopolis (modern Istanbul). Constantine died at a royal villa near Nicomedia in 337. During the Ottoman Empire, İzmit was the capital of the Sanjak of Kocaeli.

Koubaita was an inland town of ancient Bithynia inhabited during Roman times. Its name does not occur in ancient authors, but is inferred from epigraphic and other evidence.Its site is located near Gündoğdu in Asiatic Turkey.

Kocaeli University (Turkish: Kocaeli Üniversitesi) is a state university in İzmit, Turkey. It was founded as the Academy of Engineering and Architecture of Kocaeli in 1976. The electrical and mechanical engineering departments, basic sciences, and department of modern languages were the original departments of the academy. It became a part of Yıldız University in 1982, and split from it in 1992. In July 1992, the Turkish government decided to build 22 universities nationwide, including Kocaeli University. Before the 1999 İzmit earthquake, which can be regarded as the turning point for the rebirth of the university, Kocaeli University had approximately 20,000 students, 1,150 educational staff and a campus of 650,000 square meters. Kocaeli University lost nearly 75% of its physical structure in the earthquake, but its prior expansion site Arslanbey Campus rapidly compensated for the university's losses. The university moved to Umuttepe Campus in 2004. Kocaeli University's central Umuttepe Campus is located just outside Izmit in the region of Kocaeli, the most heavily industrialized region of Turkey. Most of its faculties are on this campus, except the Faculty of Fine Arts, the Faculty of Architecture & Design, the Faculty of Dentistry, and the Faculty of Animal Husbandry. Istanbul is only 90 kilometres (56 mi) away, and its secondary international airport was developed on a site 50 kilometres (31 mi) from Izmit, making the university much more accessible in recent years. Since Kocaeli is a near neighbor of Istanbul, many of its students come from Istanbul. The university 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.

Kocaeli Stadium is a stadium in İzmit, Turkey. It was opened to public in 2018 with a capacity of 34,712 spectators. It is the new home of Kocaelispor. It replaced the club's old home stadium, İzmit İsmetpaşa Stadium.

Pertev Mehmet Paşa Mosque, also known as Yeni Cuma Cami meaning "New Friday Mosque" in Turkish, is a 16th-century Ottoman mosque in the town of Izmit, Turkey. The architect was Mimar Sinan. It was built for Pertev Mehmed Paşa, an Ottoman vizier during the reigns of sultan Suleyman I and Selim II. The construction was finished in 1579. The mosque is part of a larger complex (Külliye) which originally included a madrasa, hammam, caravanserai, fountain and a lower education school. The mosque itself is a single domed structure and the dome has 24 windows. The minaret was damaged during the 1999 İzmit earthquake.

Leptoia was an inland town of ancient Bithynia inhabited during Roman times. Its name does not occur in ancient authors, but is inferred from epigraphic and other evidence.Its site is tentatively located near İzmit in Asiatic Turkey.

Kalasyrta was an inland town of ancient Bithynia inhabited during Roman times. Its name does not occur in ancient authors, but is inferred from epigraphic and other evidence.Its site is located near Solaklar in Asiatic Turkey.

Geragathe was an inland town of ancient Bithynia inhabited during Byzantine times.Its site is located north of İzmit in Asiatic Turkey.