Ploiești hosted the world's first industrial oil refinery, opened in 1856.
The refinery was built by the Mehedințeanu brothers and processed crude oil from nearby Romanian fields. Its products included lamp oil, which was increasingly valuable for lighting before widespread electric power.
Ploiești became one of Europe's most important petroleum centers because oil deposits lay close to the surface and could be transported relatively easily. Romania's petroleum industry expanded rapidly in the late nineteenth and early twentieth centuries.
The refinery is often described as the world's first systematic or industrial refinery, rather than the first place where people ever heated or distilled petroleum. Ploiești later became strategically important during both world wars because its refineries and oil fields supplied fuel to major military powers.