The ancient city walls of Phichit are located within the Phichit Old City Park, believed to have been constructed during the reign of Phraya Kotrabong for city defense. The structure consists of long earthen embankments surrounding the ancient city area. Historically, moats were dug alongside these walls to enhance defensive capabilities against invaders. Today, most of the earthen walls are covered by large trees within the arboretum, yet they still exhibit the grand scale of the ancient city layout, reflecting over 900 years of settlement history.