The historic heart of Bangkok, built on an island formed by canals and the river.
Rattanakosin is home to the Grand Palace, Wat Phra Kaew, Wat Pho and Wat Arun across the river, along with Khao San Road's backpacker scene.
This area is best explored on foot or by river boat rather than the rail network, which doesn't reach the old city directly.
Rattanakosin (the Old City) has been the ceremonial and religious heart of Bangkok since the city's founding in 1782 — the Grand Palace, Wat Phra Kaew, and Wat Pho all sit within a compact, walkable area on the eastern bank of the Chao Phraya.
See the full walking guide for a structured morning-to-evening route covering the Grand Palace, Wat Pho, a river crossing to Wat Arun, and the amulet markets near Wat Mahathat — the whole district rewards being tackled as a single dedicated day rather than piecemeal.
Khao San Road's backpacker energy, the calmer Phra Arthit riverside strip, and Banglamphu's local back lanes all sit within or adjacent to the Old City, offering a very different register from the formal temple sites.
The Old City isn't served by BTS or MRT directly — river boats (Tha Chang, Tha Tian piers) and short walks connect everything, since most sites sit within 15–20 minutes of each other on foot.