Up close, the entrance appears relatively down-to-earth. The gate is three stories high, but the guards are life-size. The sign on the wall illustrating the types of attire that are unacceptable beyond this point brings the visitor back to reality.
Inside the walls, reality is again suspended - the glittering multicoloured spires that you saw spiking the Bangkok skyline have even more fantastic glittering multicoloured bases. It is like nothing you've ever seen.
Monsters 5 metres high with green or pink faces stand guard, throwing threatening looks into the distance. Black and green stone sculptures look over bonsai trees in Chinese pots. Six foot birds of shining, coloured metal join hands and to dance around the basd of a golden spire. A mural stretches out for a hundred metres illustrating an equally long story of animal kings and battles of gods. There are flowers and incense at every other corner. Immaculate temples crowd together to create a maze of passageways, each more fantastic than the last.
This is sensory overload at its finest. The experience of walking around the Grand Palace is more like being an insect in a vast jewel box than like viewing any other "palace".
But Thailand's " Grand Palace" is much more than a royal palace. This complex of buildings is also the most important religious site in the country, and it houses the symbol of Thai sovereignty: the Emerald Buddha.
If Bangkok were London, the Grand Palace would be like having Buckingham Palace, Westminster Cathedral, the Houses of Parliament, all in one location - with perhaps the Tower of London (including the crown jewels) thrown in for good measure.
As a royal residence, the Grand Palace receives very limited use. In 1945, the King's elder brother, King Mahidol, was found shot dead in his Grand Palace quarters. The circumstances of his death have never been fully explained. This incident may be part of the reason why the present king prefers the more secure Chitlada Palace. Its extensive grounds also serve as a royal agricultural research farm.
But the King's ancestors built the Grand Palace to be lived in. Rama 1, the first king of the Chakri dynasty, began the building in 1782.
At that time, Thailand was still recovering from a devastating defeat by the Burmese. Ayuthaya, the previous capital, 40 miles upstream from Bangkok, had been occupied and sacked in 1767. The city which had been described by the Abbe de Choisy, the envoy of Louis XIV as "the most beautiful city in the East", lay in smouldering ruins. 90,000 captives were taken to Burma as slaves. The gold that had covered its temples and lined its coffers was on its way to guild temples and line coffers in Rangoon. The royal family was annihilated. It was Thailand's darkest hour.
But 15 years later, after a false start at Thonburi, Thailand was ready to rebuild at the site of a small village occupied by Chinese merchants, known as the "place of olives". The name in Thai was Bangkok.
The site was given a name more appropriate for a royal capital, "Krung Thep" - City of Angels, but it never caught on with foreigners. (Actually the name is Krungthepmahanakhorn ... plus 40 other syllables, but even the Thais can't remember all of them.)
The Chinese merchants obligingly moved a mile downstream where Chinatown still stands today.
The new kings's priority was to establish a focal point for the rebuilding of the country. Thai sovereignty, the buddhist religion, and the institution of the monarchy had all been inextricably bound together in the golden days of Ayuthaya, and these central aspects of Thai life had to be suitably housed.
Government ministers, the king's wives and children, and the principal temple of Thailand were gathered together within the walls of the Grand Palace. The country soon found the confidence to rebuild.
Wat Phra Keow, the main temple at the Grand Palace (and the name by which Thais refer to the whole Grand Palace Complex) is as close a copy of the temple at Ayuthaya as it was possible to reconstruct. Not content to claim continuity merely by architectural style, Rama 1 transported tons of salvaged building materials from Ayuthaya to be incorporated into his new Grand Palace.
Wat Phra Keow is one of the architectural treasure of Thailand, but Thais value one 75cm image housed in the temple more than any other object in the Kingdom. The Emerald buddha is considered to be the symbol of Thai sovereignty.
In the 15th century the first record of this image places it in Chiang Rai, in Northern Thailand. It was later moved to Chiang Mai and then taken as spoils of war to Laos.
In his victorious campaign to rout the Burmese invasion General Chakri liberated the image in 1779 and brought it south to the temporary capital at Thonburi, across the river from Bangkok. Later when General Chakri was invited to become king, he made a great ceremony of moving the Emerald Buddha to his Royal Chapel: Wat Phra Keow.
Naturally, the Emerald Buddha is not carved from 75cm of emerald gemstone. It is actually green jadeite. The word in Thai for the green colour of the image is the same as the Thai word for emerald.
One of the many days each year that the Grand Palace is closed or partially closed to visitors is the day on which the king changes the clothes of the Emerald Buddha. The three Thai seasons, the cool, the wet, and the hot seasons are marked by this image receiving an appropriate change of garments.
The Grand Palace is also at the centre of events for Royal Birthdays, the Royal Ploughing Ceremony, Songkran (Thai New Year), Chakri Day (the anniversary of the founding of the dynasty) and major Buddhist religious festivals.
Even though Thailand is a changing society, the significance of these ceremonies is still at the centre of Thai life. The Grand Palace is still crowded at special occasions as it has been for more than two centuries, but these days the rest of the Kingdom also watches on television.
The Grand Palace itself has changed since Rama I laid out his plans. Newer buildings have a European look, some, such as the Chakri Throne Hall, are a unique mixture of East and West.
The country Rama I ruled was a fractious agrarian society, his capital had no roads at all - only canals. Today's Thailand is rearing its head as one of Asia's economic "dragons", Bangkok is a major international city (with lots of roads and even more cars).
The national identity, the Buddhist religion, and the monarchy are at the centre of Thai life even more firmly than they were when Rama I began his building spree. For all its fanciful decoration and fantastic appearance, the Grand Palace continues to serve very well the purposes for which it was built.