On May 11, 1851, in Plovdiv, the Bulgarian writer and linguist Nayden Gerov officially organized the first holiday in honor of the holy brothers Cyril and Methodius.
The celebration takes place in the diocesan school named after the creators of the Glagolitic script.
The date was chosen because it is the common church feast of the two saints. In the Renaissance sources, the first notices of the celebration of Cyril and Methodius on May 11 are found in the “Christomatiya of the Slavic language” from 1852 to Neofit Rilski.
The Plovdiv Diocesan School, known as the First Boys' High School, is also the first in the world named after the brothers Cyril and Methodius. The story by which it got its name is fascinating. "Dr. Stoyan Chomakov and I were gathered at the house of Chorbadji Salcha Chomakov, the word was also opened about what name to give the school. I told about what the holy brothers had done, and Chorbadji Salcho marveled at their deed. Thus, by common consent, we named the school "St. Cyril and Methodius" and we ordered an icon with the face of the saints. His holiday should also be celebrated. The school introduced this holiday, which was still celebrated in the future. Following the example of the people of Plovdiv in many places around Bulgaria, they later began to call their schools after the two holy brothers", says Nayden Gerov in 1894 in his memoirs.
In 1856, Joakim Gruev proposed that the day of Cyril and Methodius be celebrated as a holiday for Bulgarian students. In 1857, the holiday was honored in the Bulgarian church "St. Stefan“ in Constantinople together with a service for St. Ivan Rilski. The following year, 1858, this day was also celebrated in Plovdiv with a solemn service in the "Holy Virgin" church, and then the teacher Joakim Gruev delivered an exciting speech about the life and work of Cyril and Methodius.
The Bulgarians themselves also at the beginning thought it was unusual to celebrate the day of the Holy Brothers and only in the fourth or fifth year of the first celebration they started coming for the celebrations. Subsequently, more and more people joined the celebrations, especially when Plovdiv acquired a Bulgarian church in 1860.
In the years after that, May 11 began to be solemnly celebrated in the Bulgarian church “St. Stephen” in Constantinople, again in Plovdiv in the church "Holy Virgin" (with a word by Joakim Gruev), in Shumen, Lom, Skopje and Sofia. The holiday began to be regularly celebrated in Shumen and Lom, since 1860, in Skopje since 1862, in Varna since 1863.
After the introduction of the Gregorian calendar in 1916, the holiday is celebrated on May 24 according to the official state calendar, and according to the church liturgical calendar, this day is dated May 11. In 1968, the Bulgarian Orthodox Church, already with the status of the Patriarchate, introduced the so-called liturgical calendar. New Julian calendar, by which the error of the old Julian calendar is removed. Thus, the day of Cyril and Methodius is honored by the Church on May 11 according to the church calendar. But due to the already established civil tradition, the secular, civil and state celebration remains on May 24, recalls in "Maritsa".
May 24 was declared an official holiday of the People's Republic of Bulgaria by a decision of the Ninth National Assembly on March 30, 1990, and since November 15, 1990, it has been an official holiday of the Republic of Bulgaria.