Most Thais have never witnessed a coronation -- it has been almost 70 years since the last one, when the young Bhumibol Adulyadej was crowned in 1950.
Bangkok has transformed from a slow-moving capital to a crowded modern city, but the spectacular three-day coronation of King Maha Vajiralongkorn will follow intricate centuries-old traditions.
From sacred water purification and a diamond-encrusted crown to a grand procession, here are five key rituals from King Vajiralongkorn's coronation this weekend:
- Royal purification -
The first day's rituals on Saturday, considered the most important, represent a symbolic transformation from the human to the divine for the monarch.
The king arrived at the palace and was led to a hall where the Supreme Patriarch, the head of the order of Thailand's Buddhist monks, blessed him with the five basic Buddhism precepts.
Then, beginning from the auspicious time of 10:09 am (0309 GMT) -- some speculate the hour reflects Rama X's reign, while "9" in Thai sounds like the word for "progress" -- the king changed from his white military uniform to a gold-lined white robe and slippers for the royal purification ceremony.
The king entered a pavilion and first anointed himself with sacred water drawn from across Thailand.
Then, a line of Hindu Brahmin priests passed him more sacred water held in royal items built during the reigns of previous kings.
They also passed him a bael leaf which he tucked behind his ear -- believed to represent victory and auspiciousness.
In the distant past, water was collected from specific rivers in India, reflecting the influential blend of Hindu and Buddhist cosmology in the coronation.
Coronation practices can be traced back thousands of years to ancient India, according to Komkrit Uitekkeng from Silpakorn University.
- The crown -
Not long after royal purification rites, the king will proceed to the Baisal Daksin Throne Hall where he will receive sacred water from eight directions.
Symbolically that "means he has received legitimacy from all directions of the kingdom", Komkrit said.
He will ascend the Bhadrapitha Throne, where in regal robes he sits under a Nine-Tiered Umbrella of State.
Brahmins will hand the monarch the royal regalia, including a wooden sceptre inlaid with gold, a precious stone-encrusted sword believed to have been found in a lake in northern Cambodia, slippers, and a whisk made from yak's hair.
The Great Crown of Victory is the centrepiece.
Tiered, gold and weighing 7.3 kilograms, it has a diamond from India at the top.
Vajiralongkorn will place the crown on his own head.
He will then issue his first royal command, which will be similar in meaning if not in wording to previous members of the Chakri dynasty, founded in 1782.
His father Bhumibol's first royal command was: "I will reign with righteousness, for the benefit and happiness of the Siamese people."
- The audience -
On Saturday afternoon, the newly-crowned king is set to grant a "grand audience" to members of the royal family, the privy council, the cabinet and senior officials.
There participants, a who's who of the powerful, wealthy and influential in junta-run Thailand, will offer their "best wishes" to the monarch.
Two hours later the king will visit the Temple of the Emerald Buddha, the most sacred space in Thailand, which on normal days is thronged with tourists.
He then symbolically moves into the Royal Residence.
- The procession -
The main element of Sunday's ceremonies, streets across Bangkok's historic heart have been blocked off in preparation for this moment.
At 4:30 pm on May 5, Vajiralongkorn will sit on a royal palanquin carried by soldiers dressed in colourful traditional garb.
A 21-gun salute will kick off the procession.
Some 200,000 people are expected to line the seven-kilometre (4.3-mile) route around the city, braving the heat.
The procession "gives the people a chance to witness for themselves that we have a new king", said Tongthong Chandransu, a researcher of royal ceremonies, who plans to watch the "great experience" in person.
It will also take the king to a number of important temples in the city where he will pray before images of the Buddha.
For many Thais, this will be their first real glimpse of a king who spends much of his time abroad.
- Meet the people -
On the last day of the ceremony Rama X will appear on the balcony of Suddhaisavarya Prasad Hall in the Grand Palace at 4:30 pm "to receive the good wishes of the people".
An hour later, diplomats will be given an audience at the Grand Palace.
This is the only time during the ceremony that representatives of foreign governments will greet the king.