Rattanakosin is the ceremonial heart of Bangkok, the island of old canals where Rama I founded the capital in 1782. Within walking distance sit the city's three headline sights -- the Grand Palace, Wat Phra Kaew with its Emerald Buddha, and the reclining Buddha of Wat Pho -- along with the National Museum and the city pillar shrine at Lak Muang.
The district rewards early starts. Arrive at the Grand Palace soon after it opens to beat both the heat and the tour groups, then wander south to Wat Pho for a traditional massage in the temple's famous school. The riverside promenades and the leafy Sanam Luang parade ground give the area a stately, low-rise feel quite unlike the rest of the modern city.
Dress modestly -- covered shoulders and knees are required at the palace and temples -- and ignore any stranger who tells you a sight is closed today. It is one of Bangkok's oldest scams, designed to steer you toward a gem shop instead.