Ploiești

Ploiești, formerly spelled Ploești, is a city and the county seat of Prahova County, Romania. Situated in the historical region of Muntenia, it lies on the Wallachian Plain, approximately 56 km (35 mi) north of Bucharest. With a population of 180,540 according to the 2021 census, it is the tenth-most populous city in the country and a major urban centre in southern Romania.
The city traces its origins to the late 16th century, when it began developing on an estate established by Michael the Brave. Located along major trade routes connecting Transylvania with the Danube basin, the settlement grew rapidly during the 17th century, gradually overtaking nearby Wallachian market towns such as Târgșor, Gherghița, and Bucov.
The local economy shifted fundamentally in 1857 with the opening of the world's first large-scale oil refinery, establishing the city as a major European centre for petroleum refining and earning it the nickname "Capital of Black Gold". Ensuing industrialisation drove sustained population growth and urban expansion through the 20th century, even amid wartime disruptions and subsequent communist economic programmes.
Today, Ploiești functions as a diversified industrial and service centre while maintaining its historical core in the energy sector. It serves as a major transport hub linking Bucharest with Transylvania and Moldavia, and acts as a gateway to the Prahova Valley tourism region.