G-03 Herakleia Pontika is the name of an ancient city, the Megara colony, which was founded at the mouth of the Lykus river in the Bithynia region, on the territory of the Thracian people called Mariandyns, in today's Kaletepe location, which dominates the harbor and coastline, and where the Tanagras in Boeotia also participated. According to the legend, its name was changed to Herakleia in 560-558 BC, referring to the Akheron cave (Cehennemağzı cave), located on the Akherousia Cape (today's Baba Cape) 2 km northwest of the city and believed to have descended underground. Located 2 miles northeast of Cape Baba, Ereğli harbor is open to the north, west and southwestern winds, and was known as "Soonautes", which means saving sailors in Antiquity.

Herakleia Pontica is a natural harbor city established on the territory of the Mariandyni people, known as the birthplace of the famous philosopher Heraclides Ponticus (387-312 BC) and the historian Memnon of Herakleia, which was frequently plundered by the Galatians and Bithynians in this period, destroyed during the Mithridatic wars. Apollonius of Rhodes stated that in the Argo Travel legend dated to the 12th century BC, the Mariandyns, the indigenous people of the region, gave the name of this hero to their city as an expression of gratitude, as they got rid of the pressure of the Bithynians with the help of Heracles. Heracleia Pontica, whose commercial power was based on the fertile lands cultivated by the Mariandyns and the naval fleet, was an important metropolitan city that could establish 41 city and village settlements, and was able to establish a local military force that could protect its independence against other city-states and even the Persian kingdom. Unlike other Black Sea cities, Herakleia Pontike produced a number of local historiographers, each of whom grew up in different periods, societies, administrations, historical and climatic conditions, and produced works of permanent importance, such as Herodoros, Promathidas, Amphitheos, Nymphis, Domitius Kallistratos and Memnon. Although Memnon of Herakleia wrote the local history of Heraklia Pontica in 16 books in the 1st century AD, the work was lost. The city of Herakleia Pontica has played a role as one of the important naval powers in the region throughout the ages and has been influenced by other cities in the Black Sea region through economic activities and commercial relations such as maritime transport and trade with other colonies. Heraclides (387-312 BC), one of the important names in the history of the city, a philosopher and astronomer who was born and raised in Heracleia Pontica. He had göne to Athens in his youth and studied in the Academy founded by Plato. He was Plato's student and suggested the theory of the Earth's rotation around its own axis. Another person, Egyptian Krispos, is the world's oldest pantomime artist who performed in Herakleia Pontica, lived and died there.

Today, the ruins of the ancient city today, which can be seen in the city of Ereğli and in the surrounding villages, Cennetağzı caves, the ancient harbor under the sea, city walls, Horse Gate, Maiden's Gate, Kaneri Gate, Herakleios Palace, Göztepe necropolis area, aqueducts, tumuli, Kaletepe ruins and observation tower, Mosaics and churches are among the important structures.