Beatrix, 75, is to sign the papers enacting the once-in-a-generation change of royal titles Tuesday morning, the central moment in several days of festivities that are already underway.
"Now that my oldest son is to take over this fine and responsible job tomorrow, it is my deep wish that the new royal couple will feel themselves supported by your loving trust," the popular monarch said in a nationally televised address. Willem-Alexander's Argentine-born wife Princess Maxima will be queen.
"I am convinced that Willem-Alexander will apply himself with true devotion for everything a good king is obliged to do."
Beatrix is hosting nobility from around Europe and beyond Monday evening for a dinner at the newly renovated national museum, the Rijksmuseum. Guests will dine in front of Rembrandt van Rijn's masterpiece, the Night Watch.
Earlier in the day, the streets of Amsterdam began flooding with orange in honor of the ruling House of Oranje-Nassau, as government and noble guests prepared for the ceremonies, and the people of the country got ready for a huge party.
In the historic city center, vendors hawked orange t-shirts, hats and feather boas. Trams flew orange flags, and Dutch flags, as did many of the boats motoring through the city's ancient canals.
Shopkeepers hung orange streamers, set out orange flower displays and rolled in countless kegs of beer.
Meanwhile, city workers finished cleaning the streets, removing unwanted bicycles and setting up temporary urinals, many of them made of bright orange plastic.
Dutch prime minister Mark Rutte told foreign journalists from more than 60 countries Sunday evening that the week's events involve an "unprecedented logistical and security operation" that was organized in just three months. Beatrix announced her intention to abdicate in January.
More than a million people are expected in Amsterdam Tuesday, with 10,000 uniformed police, 3,000 plainclothes officers and an untold number of civil servants assisting in the logistics.
The airspace above Amsterdam was closed Monday for three days. Dutch police swept Dam square for bombs, with assistance from German agents with sniffer dogs.
Royal guests from 18 countries arrived in the course of the day, and city traffic was frequently interrupted by limousines with tinted windows and police escorts.
Among the many notables on hand are Britain's Prince Charles and his wife Camilla, and the Japanese Crown Prince Naruhito and Crown Princess Masako.
Charles was also in attendance when Beatrix was crowned in 1980.
Masako's father is a judge at the International Court of Justice in The Hague. It is her first official overseas trip since the couple's 2002 visit to New Zealand and Australia.
A poll released Monday by national broadcaster NOS showed that Willem-Alexander's popularity has swelled in the run-up to his accession, mostly due to a relaxed and confident performance in an interview that was televised nationally earlier this month.
He said he's not a stickler for protocol, and he believes that "even the ultimate symbol of a ceremonial monarchy -- cutting ribbons -- can be very substantive." He explained that he will be able to indicate by his selection of which events and openings to attend the things he believes are important for the Netherlands.
He said he sees the function of the monarchy is to act as a living symbol of unity for the nation.
Beatrix succeeded her mother, Juliana, as head of state, and she won widespread acclaim and admiration from the Dutch people. Most feel she has proved a supremely competent, if occasionally aloof, head of state over her 33-year reign.
"My mother taught me that being queen is a position that you carry around with you day and night," she said once. "You can never forget about it, not for a moment."
Perhaps most tellingly, since she took office in 1980 the House of Orange has been almost scandal-free, a stark contrast to many other European royal families
Observers believe Beatrix remained on the throne for so long in part because of unrest in Dutch society as the country struggled to assimilate more and more immigrants, mainly Muslims from North Africa, and shifted away from its traditional reputation as one of the world's most tolerant nations.
In recent years, speculation about when she might abdicate had grown, as she endured personal losses that both softened her image and increased her popularity further as the public sympathized.
Her husband Prince Claus died in 2002; and last year she was devastated when her youngest son, Prince Friso, was hit by an avalanche while skiing in Austria and suffered severe brain damage. Friso remains in a near comatose state.
In the most emotional part of her farewell Monday, she praised Claus for teaching their children to be attuned to changes in society.
"Prince Claus brought our House closer to this time," she said. "Possibly history will show that the choice of this husband was my best decision."
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