The funeral of Britain's Queen Elizabeth II today will see the biggest gathering of royalty this century -- perhaps ever -- in London.
Reigning monarchs, crown princes and royals representing tens of millions of people are expected to arrive from the Middle East and Asia.
But it is members of European royal houses who had a particularly close relationship with Her Majesty, some as friends and many as relatives.
So who is attending the funeral, and how are they related to Queen Elizabeth II, if at all?
Here's our guide:
King Philippe and Queen Mathilde will be representing Belgium at the funeral on Monday.
Following Queen Elizabeth II's death, the household released a message saying: "We will always keep fond memories of this great Lady who, throughout her reign, showed dignity, courage and devotion. Each of our encounters will remain etched in our memories forever."
And how are the two royal families related? King Philippe's ancestor is King Leopold I, the first King of the Belgians, who was also Queen Victoria's uncle. And Queen Victoria was Queen Elizabeth II's great-great-grandmother.
Denmark's Queen Margrethe II will be attending the funeral, just a week after celebrating the 50th anniversary of her own reign, along with her son Crown Prince Frederik.
Queen Margrethe II was a third cousin of Queen Elizabeth II, and the monarchs were descendants of both Queen Victoria and also King Christian X of Norway (he was Magrethe's grandfather, and Elizabeth's two-times great uncle by marriage).
"Your mother was very important to me and my family," Queen Margrethe wrote in a letter to Britain's King Charles III.
"She was a towering figure among European monarchs and a great inspiration to us all."
Following the death of Queen Elizabeth II, the Danish royal household changed some of the plans for Queen Margrethe's anniversary celebrations that same weekend, including cancelling a military parade as a mark of respect.
Crown Prince Frederik met his future wife Mary, an Australian, at the Sydney Olympics in 2000. Queen Margrethe's late husband Prince Consort Henrik was a former French diplomat, he died in 2018.
The House of Liechtenstein dates back to the early 1600s, and the royal family gives its name to the tiny European country of just 38,000 people.
The royal household confirmed to Euronews that His Serene Highness Hereditary Prince Alois and his spouse Her Royal Highness Hereditary Princess Sophie will both be attending the funeral of Queen Elizabeth II.
Prince Alois rules Liechtenstein jointly with his father, Hereditary Prince Hans-Adam II, who was an eighth cousin of Queen Elizabeth II - both were descendants of Ludwig, Duke of Brunswick-Wolfenbüttel.
"Hereditary Prince Alois, who will be attending the funeral, therefore is the ninth nephew of H.M. Queen Elizabeth II," the Liechtenstein royal household said.
Somewhat curiously, Princess Sophie -- who was born into a Bavarian aristocratic family -- can trace her relatives directly back to Scotland's Bonnie Prince Charlie, whose descendants have a hypothetical claim to the crown: which makes Sophie second in line to become the Jacobite Queen of England and Scotland - although her uncle, who is first in line, has described the claim as purely "hypothetical" at this point!
Grand Duke Henri and Grand Duchess Maria Teresa of Luxembourg will be attending Monday's funeral, and they have a very special connection to the UK.
Henri's mother, Grand Duchess Charlotte, fled Luxembourg after the German invasion in WWII and was exiled to London for two years. During that time she broadcast messages on the BBC and became a symbol of her country's resistance during the war.
"The Queen played a considerable part in shaping the history of the United Kingdom as its longest-serving monarch. We profoundly admired Her moral strength and determination. She was an exemplary monarch, most loved and respected by people all over the world," Grand Duke Henri wrote to King Charles III.
"Luxembourg has never forgotten the extraordinary support the United Kingdom gave to Grand Duchess Charlotte and her son, my father Jean, during World War 2. Their safe haven in London helped to preserve the very existence of my country in those dark times.
"We are grateful for the close ties of our families and Her Majesty’s extraordinary and unique example of service to our country."
The Grand Duke and Queen Elizabeth were both related to Britain's King George II and Queen Caroline, who ruled in the mid-1700s.
The Monégasque Royal Family will be represented at the funeral by Prince Albert II and Princess Charlene.
"Her Majesty’s unwavering commitment and dedication to duty during Her reign has always been extremely inspiring. It will be long remembered and admired" Prince Albert wrote in a letter to King Charles III last week.
"She truly represented the unity and dignity of the United Kingdom throughout the last seven decades."
The House of Grimaldi has ruled the tiny Mediterranean principality for 700 years, and during the 20th century became a symbol of glittering, modern European royalty when Prince Albert's father married Hollywood star Grace Kelly after meeting at the Cannes Film Festival. But tragedy struck when Princess Grace died in a car crash in 1982.
Like the Danish Crown Prince and Princess, Monaco's Albert and Charlene met at the Sydney Olympic Games in 2000, where she was a South African swimmer.
The Dutch royal family have traditionally been close to their British counterparts, and this is why King Willem-Alexander and Queen Máxima will be attending the funeral in London, along with the former's mother, the previous queen who abdicated in favour of her son in 2013 and is now styled as Princess Beatrix.
"We remember Queen Elizabeth II with deep respect and great affection. Steadfast and wise, she dedicated her long life to serving the British people," the Dutch royals said in a statement.
"We feel a strong bond with the United Kingdom and its royal family, and we share their sorrow at this time. We are very grateful for our countries' close friendship, to which Queen Elizabeth made such an unforgettable contribution."
King Willem-Alexander and Queen Elizabeth II were related as fifth cousins - he is a descendant of Princess Carolina, the daughter of King William IV; while she was also related to Princess Carolina through her grandmother Queen Mary.
King Harald V and Queen Sonja of Norway will be attending the funeral of Queen Elizabeth II, and the Norwegian royals have some of the most enduring ties to Britain and the British royal family of any in Europe.
"For nearly a century, Her Majesty devoted her life to the service of the Commonwealth, following the British people through good days and bad, in times of happiness and sorrow," King Harald said in a statement marking the death of the Queen.
Queen Elizabeth II and King Harald were second cousins, sharing the same great-grandparents, King Edward VII and Queen Alexandra, who were the father and mother of Norway’s own Queen Maud.
When Norway was occupied by Germany in 1940, King Haakon and Crown Prince Olav (the current king's grandfather and father) were forced to flee the country and live in exile in London. "This brought the two branches of the family even closer together," the Norwegian royal household said in a statement.
When she was young, Queen Elizabeth II used to call King Haakon "Uncle Charles" and according to the Norwegian royal family, "Uncle Charles” was The Queen’s favourite uncle - and she named Prince Charles after King Haakon.
Noway was the first country outside the Commonwealth that Queen Elizabeth paid a state visit to, in 1955, and she visited three times in total, as the guest of three generations of Norwegian kings.
Since 1991 when King Harald and Queen Sonja were coronated, they have paid an annual visit to the United Kingdom to visit their British relatives in the royal family.
Two generations of Spanish royalty will attend the Queen's funeral: the current King Felipe VI and Queen Letizia, and Felipe's parents former King Juan Carlos and Queen Sofia.
In a telegram sent to Buckingham Palace, King Felipe said that the Queen's "sense of duty, commitment and lifetime of service to the people of the United Kingdom and Northern Ireland were an example to us all and will remain a strong and valuable legacy for future generations".
Speaking at an event in Seville this week, the King of Spain told the audience that it was not easy to convey faithfully "our deep personal, family and institutional feelings of loss at her absence and of immense respect for her".
King Felipe was the Queen's third cousin - and affectionately called her "Auntie Lilibet" - while his father King Juan Carlos is the great-great-grandson of Queen Victoria.
The House of Bernadotte is one of Europe's grandest royal families, and also among the most closely related to the British royals.
King Carl XVI Gustaf and Queen Silvia will be attending the funeral in London and released a heartfelt statement on the death of Queen Elizabeth II.
"She has always been dear to my family and a precious link in our shared family history," the king wrote.
The King of Sweden marked his 49th anniversary since ascending to the throne this week, in a reign marked by a period of modernisation - he made it possible for his oldest child, Crown Princess Victoria, to be his heir, when previously it was only male children who could inherit the crown.
So how closely are the two great European houses, Sweden and Britain, related, and what about links to other Scandinavian royalty?
In the simplest terms, both King Carl XVI Gustaf and Queen Elizabeth II shared the same great-great-grandmother, Queen Victoria. (In more complicated terms, the King is also related on his mother's side to Queen Victoria's eighth son Prince Leopold).
And across the region, King Carl XVI Gustav is the cousin of Queen Margrethe of Denmark as they both have the same grandfather; while the Swedish monarch is second cousin to King Harald V of Norway, because Harald's mother was born a Swedish princess.
Other royals who could be attending the funeral
Some other European royal figures could also be attending the funeral, but who are no longer part of reigning families.
King Constantine II and Queen Anne-Marie of Greece. Although the Greeks abandoned the monarchy in the early 1970s, the last king and queen are likely to attend the funeral of Queen Elizabeth II due to close family relations.
Queen Anne-Marie is the youngest sister of Denmark's Queen Margrethe II. She is also a first cousin of King Carl XVI Gustaf of Sweden and a second cousin of King Harald V of Norway. She is a third cousin of her own husband King Constantine, as they both have King Christian IX of Denmark as a great-great-grandfather.
Queen Elizabeth II and Queen Anne-Marie have the same great-great-grandmother: Queen Victoria.
Meanwhile, King Constantine is a close friend and second cousin of King Charles III, and godfather to Prince William the new Prince of Wales. He was also related to the Queen's husband Prince Philip.
Crown Prince Alexander of Yugoslavia is the heir to a royal dynasty that was last in power in 1945. He was born in London during WWII and christened at Westminster Abbey with King George IV and then-Princess Elizabeth as his godparents.