In the late 18th century, Siam faced numerous challenges, including threats from foreign powers and internal strife. King Buddha Yodfa Chulaloke, also known as King Rama I, recognized the urgent need to establish a secure and strategically located capital. He chose a site on the eastern bank of the Chao Phraya River, which was advantageous for defense and trade. The city was built as a fortified area, with walls and military installations ensuring its protection. This marked the establishment of Rattanakosin, laying the foundation for modern Bangkok.

The construction began with the royal palace, Wat Phra Kaew (Temple of the Emerald Buddha), and a grid layout of roads, which facilitated the organization of the city's districts. The architecture reflected a blend of traditional Thai and European influences, creating a unique aesthetic that would characterize the city for generations. The establishment of Rattanakosin symbolized the revival and consolidation of the Thai state, transitioning from the earlier Ayutthaya period to a new era.

Over the years, Rattanakosin grew in both size and significance, transforming into a cultural, political, and economic center of Thailand. The initial establishment laid the groundwork for various institutions and developments that would influence the region significantly. Markets sprang up, attracting merchants from near and far, thus cementing Bangkok’s status as a trade hub and increasing its importance both locally and internationally.