Rattanakosin, Banglumpoo, Khaosan Road (yellow zone in the map*)
Rattanakosin is the historic district, the origin of modern Bangkok and its spiritual centre. The Temple of the City Pillar is here, which means that this is kilometre zero not only of the city but also of the country.
The first king of the current Chakri dynasty, Rama I, moved his residence from the other side of the river (Thonburi) to the present location of the Grand Palace. To do so, he created an artificial island emulating the former capital of the Kingdom of Siam, Ayutthaya.
As a reference to get oriented and organize the visit, you can use the great Ratchadamnoen Avenue and the Monument to Democracy, in addition to the Grand Palace.
On both sides are streets with buildings of four or five heights and facades darkened by humidity and the passage of time. A neighbourhood atmosphere with streets full of life, this is the old Bangkok of Banglumpoo and Khaosan Road within it.
There are two high spots from which you can enjoy a beautiful aerial view, the Wat Arun and the Wat Saket on the Golden Mountain.
Both locations are at the ends (west-east). To get an idea of the distances, walking from the nearest dock of Wat Arun (Tha Tien pier) to the Golden Mountain can take you little more than half an hour.
They are affordable distances, though if the heat is strong, the tuk-tuk is a good solution.
Places of interest:
Grand Palace and Wat Phra Kaew, Wat Pho, Wat Arun and Royal Barge Museum (crossing the river), Sanam Luang esplanade, Wat Bowoniwet Wihan, Wat Saket and Golden Mountain, the City Pillar, Amulets Market, Museum of Siam, Borombhiman Hall, Wat Mahathat, Monument to Democracy, Rachadamnoen Boxing Stadium.
Sukhumvit Leisure area (blue zone*)
The district of Sukhumvit extends along the main avenue, Sukhumvit Road, the longest in Thailand, and the successive perpendicular streets (soi) on both sides.
This is another accommodation area with hotels for all budgets.
Unless you have the hotel here or for some particular reason, this area is not very interesting in the daytime.
What we mean is that for occasional visitors we can characterize Sukhumvit as a leisure area that stands out after sunset, with luxurious hotels, spas and massage parlours, cocktail bars, restaurants, nightclubs, rooftop bars and a few residential areas in quiet areas at half-light.
In short, shopping, eating, relaxing and nightlife.
Here you will find a part of what we usually call red-light district: Soi Cowboy and Nana Square.
Places of interest:
Arabian Town, Khamthieng House Museum, Japanese Food Zone, Benchasiri Park, Terminal 21, The Emporium.
Terrace Restaurants: Octave Rooftop, Above Eleven, Sky Rooftop, L’Appart Sofitel, Long Table.
Nightclubs: Sing Sing Theater, Insanity, Levels Club, Beam, Glow, Iron Fairies, Titanium Ice Bar.
Siam Commercial district (green zone*)
Bangkok is in itself a vast centre of production and distribution of all kinds of products; however, there are reasons to say that Siam is one of its lungs.
What makes this area unique is the concentration of modern shopping centers, its variety and the offer of complimentary leisure, for instance, cinemas, restaurants, an oceanarium, the Madame Tussauds wax museum or Kidzania, etc.
Shopping, from the cheapest goods to the most luxurious ones. At one extreme we can place the MBK Center, which might be regarded as a kind of street market with hundreds of small shops. At the other end is placed the Siam Paragon, where we find exclusive stores such as Louis Vuitton, Rolls Royce or Cartier, along with international brands, such as Zara or Hard Rock Cafe.
This area is interesting for those who want a day of shopping or simply stroll and nose around what is also pure Bangkok.
Silom Financial district - Riverside (purple zone*)
This is the financial district of the city, with the typical image of a grand avenue full of modern office buildings, very colorful at the junction of Sathon Road with N.Rajanagarindra Road.
The first section of Silom Road, which starts at one of the corners of Lumpini Park, is one of the busiest points of the city. Out of office hours, the movement of people is almost frantic, with narrow sidewalks in which spreads many street food stalls.
The Lumpini Park is worth a visit, especially at dusk after six, when it is full of sportsmen, aerobics groups and ballroom dancing, among others (better 15 minutes before, at 5h45, you will discover the reason right there). The atmosphere is delightful and walking around its lakes evokes the picture of Central Park in New York. It closes its doors at 21h00.
You can find from cheap guesthouses to fancy hotels.
Here is located the Serpentarium of the Queen Saovabha Memorial Institute, where it is possible to attend the poison extraction at 11h00 (every day) and an exciting show with these fearsome ophidians at 14h30 (except holidays).
It is also a leisure and restaurant area, where the Patpong night market is laid. On the sides, there are a few bizarre shows of sexual content.
The extension of Silom to the Chao Phraya takes us to a section of the river in which are luxurious hotels as renowned as the Mandarin Oriental and Shangri-La.
Chinatown, authentic piece of China (pink zone*)
The neighborhood in which the Chinese diaspora settled from the very birth of the city, authentic and bustling. A must-see during your visit to Bangkok.
More information in the specific article on Chinatown.
Places of interest:
Wat Traimit, Yaowarat, Odeon Circle, Sampeng Market, Phatthurat Market, Wat Mangkon Kamalawat.
Chatuchak markets area (orange zone*)
In the north of the city and accessible with both the Skytrain BTS and the subway MRT, in this area there are three popular markets in Bangkok, especially the weekend one.
Fresh products at the Or Tor Kor market, weekend at Chatuchak and JJ Green Market, a hot night market from Thursday to Sunday.
More information in the specific post of top markets in Bangkok and a second post only about Chatuchak market.
Places of interest:
Queen Sirikit Park, Chatuchak Weekend Market, Or Tor Kor Market, JJ Green Market.