Si Thep Historical Park is an archaeological site in Phetchabun Province, Thailand, that contains the ruins of an ancient city that dates back to the Dvaravati period, between the 7th and 11th centuries. The site was once a thriving city that was a center of trade and culture, and was also an important religious center.

The park covers an area of approximately 720 acres and contains numerous ruins and structures, including the remains of several temples, palaces, and fortifications. Some of the most notable structures include the ruins of Wat Phra Si Iriyabot, a temple that was built during the 9th century, and the remains of the city walls, which are over 2,000 years old.

One of the most impressive features of the site is the Si Thep Stupa, which stands at the center of the city and is believed to have been built during the 9th century. The stupa is a towering structure that rises over 25 meters into the sky, and is decorated with intricate carvings and sculptures.

Si Thep Historical Park is a fascinating place to explore for anyone interested in history or archaeology, and offers a glimpse into Thailand's rich cultural heritage. Visitors can explore the various ruins and structures, learn about the history of the site at the on-site museum, and enjoy the natural beauty of the surrounding area.