Si Thep Historical Park (Thai: อุทยานประวัติศาสตร์ศรีเทพ) is an archaeological site in Thailand's Phetchabun province. It covers the ancient city of Si Thep, a site inhabited from around the third to fifth century CE until the thirteenth century, spanning cultural periods from late prehistory, through Dvaravati Empire, to the golden age of the Khmer Empire.
Si Thep was one of the largest known city-states that emerged around the plains of central Thailand in the first millennium, but became abandoned around the time the Thai-speaking cities of Sukhothai and later Ayutthaya emerged as new centres of power in the Chao Phraya River basin. The site gained the attention of modern archaeology in 1904 following surveys by Prince Damrong Rajanubhab, and it was listed as an ancient monument in 1935.