Queen Margrethe II, Denmark's longest reigning monarch, is due to pass the throne to her first-born son Frederik on Sunday and tens of thousands of Danes are expected to gather in the streets of Copenhagen to witness the historic succession.

Margrethe stunned the nation of nearly six million on New Year's Eve when she announced her decision to abdicate after 52 years as queen, becoming the first Danish monarch in nearly 900 years to relinquish the throne.

People from all over Denmark are expected to crowd Copenhagen in a sign of the huge popularity the monarchy is enjoying.

"The royal family means everything that is Danish. It's fairytales and traditions," said Anna Karina Laursen, 59, a nod to the country's famous fairytale writer Hans Christian Andersen.

The crown prince, 55, and his Australian-born wife Mary, 51, who will become queen, are scheduled to leave the royal palace at 1235 GMT in a 1958 Rolls-Royce. Margrethe, 83, will follow by horse carriage a few minutes later to take her final ride as monarch through the streets of the capital.

There will be no coronation as in Britain, but the succession itself will take place at around 1300 GMT, the moment Margrethe signs the declaration of her abdication.

This will take place during a meeting of the Council of State at parliament where the government, Frederik and his oldest son Christian, 18 years old and the new heir to the throne, will participate.

Roughly one hour later, Prime Minister Mette Frederiksen will proclaim the new king on the balcony of the parliament and Frederik will give a short speech, before the new king and his wife ride by carriage back to the palace.

The Amalienborg complex, built in the 1750s, is located in central Copenhagen and consists of four palaces built around an octagonal courtyard. It is home to both the outgoing queen and the new reigning couple.

Hotel operator Scandic's property situated just around the corner from the royal palace sold out of rooms just two hours after Margrethe announced her abdication and has seen 50% more bookings this weekend than it usually does in mid-January, commercial director Klaus Johansen told Reuters.

ROYAL POWER COUPLE

Margrethe, who in the past had said she would remain on the throne for life, did not give an exact reason for her decision to step down but said that a major back surgery she underwent in February last year had made her consider her future.

"It could be that she thinks Prince Frederik is prepared to take over now," said Lars Hovbakke Sorensen, a historian and associate professor at University College Absalon in Denmark.

"He's 55, and maybe the queen wanted to avoid a situation where you would have a very, very old king, as you saw with Prince Charles." The British king was 73 when he ascended the throne after his mother Queen Elizabeth died in September 2022 aged 96.

The new Danish royal couple will take the throne at a time of huge public support and enthusiasm for the monarchy. The most recent survey done after the queen announced she would abdicate indicated that 82% of Danes expect Frederik to do well or very well in his new role, while 86% said the same about Mary.