On Saturday, 9th December 1531, Blessed Mother Mary appeared to Saint Juan Diego at Tepeyac Hill in Mexico City. That morning, when Juan Diego reached Tepeyac Hill while heading to church at Tlatelolco, he heard beautiful music, and saw a white radiant cloud at the top of the hill. Suddenly, the song stopped and a beautiful, gentle, and graceful woman’s voice called his name, Juanito, Juan Dieguito!
Juan Diego quickly climbed the hill, and a very beautiful, young woman with garments shining like the sun revealed herself to Saint Juan Diego. The “woman clothed with the sun” asked, “Juanito, my son, where are you going?” Saint Juan Diego responded, “Noble Lady, my Queen, I am going to the Mass in Mexico City to hear the divine things that the priest teaches us there.”

The Virgin of Guadalupe continued, “I want you to know for certain, my dear son, that I am the perfect and always Virgin MARY, Mother of the True God from Whom all life comes, the Lord of all things, Creator of Heaven and Earth. I greatly desire that a church be built here in my honor, in which I will show my love, compassion, and protection. I am your Mother full of mercy and love for you and all, trust in Me. I will hear their complaints and I will comfort their afflictions and their sufferings. So that I might show all My love, go now to the bishop and tell him that I am sending you.”
Obediently, Juan Diego went to the Bishop’s house, where he was warmly received. The Bishop attentively listened to Juan Diego, but there was hesitation with regards to his story and the instructions from the Woman of the Tepeyac. The Bishop requested time to consider the matter.
In the evening, while returning home, The Queen of Heaven appeared to Saint Juan Diego for the second time. Disappointed that he had not accomplished his mission, Saint Juan Diego requested Mother Mary to send a more esteemed person whom the Bishop would believe. Mother Mary’s response was; “My dearest son, you must understand that there are many more noble men to whom I could have entrusted my message and yet, it is because of you that my plan will succeed. Return to the bishop tomorrow. Tell him that it is I myself, the Blessed Virgin MARY, Mother of God, who am sending you.”
The next day, on Sunday, 10th December, after the morning Mass, Saint Juan Diego went to the Bishop’s house for the second time. This time, the Bishop asked for a truly acceptable, miraculous sign to prove Blessed Virgin Mary’s identity. He discreetly sent two servants to follow Saint Juan Diego on his way home, but when Saint Juan Diego reached the Tepeyac, he disappeared from the servants’ sight. The servants could not find Saint Juan Diego despite searching the hill and the surrounding area. They went back to the Bishop with no answer.
However, during this time when the servants were searching in vain for Saint Juan Diego, the humble peasant was having his 3rd encounter with “The Lady from Heaven”. Saint Juan Diego told Mother Mary that the Bishop wanted a sign, and Our Lady of Guadalupe promised a sign for the Bishop when Saint Juan Diego would return to her the next day.
On 11th December, Saint Juan Diego missed the appointment with Our Lady, as he was looking after his sick uncle. On 12th December, Juan Bernardino’s health deteriorated further, therefore, Saint Juan Diego went to Tlatelolco to seek a priest to administer the sacraments to his dying uncle. He took a different route around Tepeyac Hill to avoid encountering Blessed Mother Mary because he was embarrassed that he had missed the previous day’s appointment with Her, and he also did not want Her to delay him.

Still, Our Lady encountered Saint Juan Diego, asking him where he was going. After his explanations, Blessed Mother Mary asked him, “Am I not here, I who am your Mother” (¿No estoy yo aquí que soy tu madre?), and then assured him that his uncle was already cured. She instructed him to gather roses on the top of the Hill, and bring them to Her.
Trusting our Blessed Mother, Saint Juan Diego found the most beautiful and sweet-smelling Castilian roses, not native to Mexico, blooming at the top of the frozen and barren hill. He collected and arranged them in his cloak/tilma, returned to the Virgin Mary, who touched the roses.

Saint Juan Diego then rushed to the Bishop’s house, and patiently waited for hours before he was shown to the Bishop. He told the Bishop what had happened and unfolded his tilma as the evidence the Bishop wanted. The roses, still shining with dew, scattered to the floor, and the Bishop fell to his knees and admired the tilma where the very beautiful and full of gentleness supernatural image of the Virgin Mary appeared.

Immediately, the Bishop comprehended the truth of Our Lady of Guadalupe’s message through Saint Juan Diego. He took the Castilian roses and the tilma, and respectfully put them in his private oratory.
Saint Juan Diego went and found his uncle fully recovered, as assured by the Queen of Heaven. Our Lady of Guadalupe’s fifth apparition had taken place at the little home where Juan Bernardino was staying. After praying at his bedside, the Virgin of Guadalupe appeared to him, and healed his deadly sickness.
Bishop obeyed Our Lady of Guadalupe, and built the chapel on the Tepeyac Hill. Over the years, millions of people have visited the Shrine of Our Lady of Guadalupe in Mexico witnessing many miracles through the intercession of Our Lady of Guadalupe. The Feast of Our Lady of Guadalupe is celebrated every 12th December.
Interesting details on the image of Our Lady of Guadalupe
Source https://guadalupeshrine.org/our-lady-of-guadalupe-shrine/#juan_diego
Source: https://www.ewtn.com/catholicism/saints/our-lady-of-guadalupe-424