The coronation of King Ferdinand I and Queen Maria, as sovereigns of Greater Romania, would consecrate the act of Union on December 1, 1918. The chosen place was not accidental, the city of Alba Iulia having a historical precedent: in 1599, in the same place, the ruler Mihai the Brave united the three Romanian Countries. For the coronation ceremony, the Coronation Cathedral, also known as the Cathedral of the Reunification of the Nation, was built, the plans being signed by the architect Victor G. Ştefănescu, a student of the famous architect Ion Mincu, and the interior painting, executed by the sculptor of the Royal Court, Costin Petrescu, the creator of the sketches for the royal mantles.

The sovereigns first attended a religious service celebrated by the Patriarch of Romania, Elie Miron Cristea, and the metropolitans of the Romanian provinces. After the divine service, the coronation took place on the platform in front of the cathedral, so that it could be "seen by the entire people" participating in the event. King Ferdinand I and Queen Maria, dressed for the ceremony, wore on their shoulders mantles woven from purple and edged with ermine fur. After placing the steel crown on their heads, with which the first king of Romania, Carol I, had also been crowned, Ferdinand I "then placed the golden crown on the head of his kneeling wife." Cannon salutes announced that the first sovereigns of all Romanians had received the divine consecration of their "function".

The entire coronation ceremony was lavish, Queen Mary, of British and Russian blood, taking over much of the Byzantine tradition, whose shadows greatly influenced, through their spirit, the European monarchies. She asked all the ladies of the royal family, who were part of the procession, to dress in gold, and the others to wear purple and silver. "I do not want a modern coronation, as another Queen might have. Mine should be entirely medieval." - said the sovereign.

Queen Maria's coronation cloak is preserved in the heritage of the Peleş National Museum, as is the cloak of King Ferdinand I. True works of art, they were crafted with great artistic talent and skill, the two pieces being, in general, similar. The artistic conception belongs to the painter of the Royal Court, Costin Petrescu (1871 – 1954), made between 1921 – 1922. It is a unique piece, executed at the order of the Royal House on the occasion of the coronation in Alba Iulia, on October 15, 1922. The queen's cloak was inspired and executed after a Byzantine model, the embroideries being made by Elena Niculescu Frunzeanu, the director of the Sericulture and Weaving School in Bucharest. The embroideries were presented at a fabric exhibition in June 1921, an exhibition visited by Maria. "I think the cloak will be beautiful and effective, although if I were allowed to design it myself, I would do something even more artistic," said the queen.

It is a ceremonial piece, made of lamé fabric and gold thread, with silk embroidery and semi-precious stone applications, with the emblems of all the provinces that formed Greater Romania woven into it. Golden in color, the mantle is embroidered with ears of wheat and sheaves, representing “the main wealth of the Romanian land.” The border is made of ermine, along the entire edge of the mantle, completed towards the inside with a purple-cardinal embroidered silk border, widening in a semicircle around the neck, with the monogram of Queen Maria, surmounted by a royal crown. On the oval edge there is a silk border, with seven heraldic insignia: the coat of arms of the Hohenzollern family, of Wallachia, of Moldavia, of Transylvania, of Oltenia and Banat, of Dobrogea, the coat of arms of the Edinburgh family, separated by groups of ears of wheat. Cross-shaped motifs are applied over the entire surface. “(…) the mantle is overwhelming. – the queen wrote in her Notes – I look like those statues of the Virgin that, in Catholic countries, are specially dressed and adorned with jewels on feast days and carried through the streets in processions. The color of gold, used for the toilet and mantle, is absolutely superb. Worked on a background of red silk thread, it has splendid shadows, like a sunset. (…) The color of gold and everything harmonizes unusually well with my complexion, with my blond hair and character in general. I am, of course, a mon avantage in this difficult outfit and, as I have a reputation for not giving up, from the point of view, as a woman, it is important, because on this great day, as queen of my people, I want their hearts to beat for me with pride. I do not want to disappoint them, I have this ambition.”