Prang Khaek is a complex of three brick towers built in the Khmer Pakhuo style, making it the oldest historical site in Lopburi. The architectural highlight is the mortarless bricklaying technique, where bricks were polished smooth and stacked tightly together, a rare ancient craft. During the reign of King Narai the Great, the site was restored, and a brick-and-plaster vihara with pointed arched windows was added. The monument stands on a traffic island in the heart of the city, symbolizing the coexistence of ancient civilization and modern urban life. At night, the towers are beautifully illuminated, creating a mystical and majestic sight perfect for sightseeing and historical photography.