Sinaia is a town and a mountain resort in Prahova County, Romania. It is situated in the historical region of Muntenia. The town was named after the Sinaia Monastery of 1695, around which it was built. The monastery in turn is named after the Biblical Mount Sinai. King Carol I of Romania built his summer home, Peles Castle, near the town in the late nineteenth century.

Sinaia is about 65 kilometres (40 miles) northwest of Ploiesti and 48 kilometres (30 miles) south of Brasov, in a mountainous area on the Prahova River valley, just east of the Bucegi Mountains. The town's altitude varies between 767 to 860 metres (2,516 to 2,822 feet) above sea level.

The city is a popular destination for hiking and winter sports, especially downhill skiing. Among the tourist landmarks, the most important are Pele? Castle, Pelisor Castle, Sinaia Monastery, Sinaia Casino, Sinaia train station, and the Franz Joseph and Saint Anne Cliffs. Sinaia was also the summer residence of the Romanian composer George Enescu, who stayed at the Luminis villa.