Few figures in European history have left a cultural footprint as deep and enduring as 9th century saints Cyril and Methodius. Revered as the Apostles of the Slavs, the two brothers from Salonica, the modern  Greek city of Thessaloniki, are remembered as missionaries, scholars, translators and creators of the first Slavic alphabet. Their legacy bridges cultures, languages and centuries.

In 1980 Pope John Paul II proclaimed them co-patron saints of Europe, acknowledging that their work helped shape the cultural and spiritual identity of a large part of the continent. Yet their significance goes far beyond church history. Cyril and Methodius represent a powerful symbol of intellectual achievement, cultural dialogue, and the transformative power of language.

The stained-glass portrait of Cyril and Methodius is the centrepiece of the main staircase at Sofia University

Across Central and Eastern Europe, many nations have embraced their legacy as part of their own historical narrative. At different moments in history, their story has been invoked in struggles for independence, cultural recognition and national identity. Today, however, their heritage also stands for something broader: a reminder of the shared values and cultural connections that bind Europe together.

For Bulgarians, the mission of Cyril and Methodius carries a particularly rich meaning. It evokes emotions ranging from patriotic pride to nostalgic reverence, yet it is almost always perceived as part of Bulgaria's own historical heritage. From a wider European perspective, however, their work represents a major civilisational milestone. It helped integrate the Slavic regions of Central and Southeastern Europe into the sphere of European Christian culture.

Written in late 10th or early 11th century, in Preslav, the then capital of Bulgaria, Codex Surpasliensis is the largest extant Cyrillic manuscript from the First Bulgarian Kingdom

In the mid-9th century, Constantine the Philosopher – later known also as Cyril – created, with the assistance of his brother Methodius, the Glagolitic alphabet. This innovative writing system was designed to reflect precisely the sounds of the East Bulgarian dialect spoken by the Slavic population around Salonica. The alphabet broke away from the dominant Greek-Latin model of written culture and achieved something revolutionary for its time: it codified a spoken vernacular language into a literary one. The language used in these texts was the Slavic language of the Bulgarian communities around Salonica.

At the request of the ruler of Great Moravia, a powerful Central European principality, the brothers brought this alphabet northward. There, they used it to translate the Holy Scriptures and liturgical texts into the Slavic language – an unprecedented step that allowed ordinary people to hear and read sacred texts in their own tongue.

Monument to Cyril and Methodius in Ohrid, North Macedonia. In the 9th and 10th centuries, the city was part of medieval Bulgaria and was one of the centres where local scribes transformed the Glagolitic script, created by Cyril and Methodius, into the Cyrillic alphabet

After the deaths of the two brothers and the collapse of the Moravian mission, their disciples found refuge in the recently Christianised Bulgarian state, under the enlightened ruler Prince Boris I.

In Bulgaria, their work flourished. Building upon the Glagolitic tradition, the disciples created the Cyrillic alphabet, named so to honour their teacher, Cyril. At the same time, they produced a vast body of literature that laid the foundations of Old Bulgarian literature and the broader Slavic literary tradition.

With this development, Europe gained its third major writing system, alongside the Latin and Greek alphabets. From that moment onward, the work of Cyril and Methodius became permanently associated with Bulgaria.

Statue of Cyril and Methodius (left) from the Charles Bridge in Prague, Czechia. The brothers' mission in Moravia was an important step in their quest to create and spread the Slavic alphabet in Europe

It is therefore not surprising that when Bulgaria joined the Council of Europe in 1992, the country was described as the land of Saints Cyril and Methodius and of the Cyrillic alphabet, a nation that both shares and preserves Europe's common cultural heritage.

One of the most important initiatives dedicated to studying and preserving this heritage is the European Cultural Route of Ss Cyril and Methodius. It encompasses numerous historical landmarks, natural heritage sites, and UNESCO World Heritage locations across the lands once travelled by the creators of the Slavic alphabet and their disciples in the 9th century.

The journey begins in Thessaloniki, the birthplace of the two brothers. The modern tradition of honouring them there dates back to 1880, when the patron feast of the Bulgarian boys' high school was celebrated. By the 1980s, the city was observing 11 May, the church feast of the enlighteners, with major public celebrations.

In Istanbul (Byzantine Constantinople), where Cyril both studied and taught, their memory is honoured in the intriguing Bulgarian church of St Stephen, known as the Iron Church. The Bulgarian Sunday School there is also named after them.

Glagolitic inscription from Zagreb Cathedral, carved in 1942, commemorating the adoption of Christianity by Croats in the 7th century. Croatians used the Glagolitic from the 9th century well into the 19th century

Cyril spent his final years in Rome, where he was buried in the Basilica of Saint Clement. This site remains the central location for Cyril and Methodius celebrations in the city today.

Methodius was later appointed Archbishop of Pannonia but faced fierce opposition from the Bavarian clergy and was subsequently imprisoned. After his release, he returned to Moravia and devoted the remainder of his life to an extraordinary mission: translating the entire Bible and numerous other texts into Slavic.

Following his death, many of his disciples were persecuted or expelled. Some eventually reached Bulgaria, where they were welcomed and tasked with establishing major literary and educational centres in Pliska, Preslav, and Ohrid (now in North Macedonia). There, the Glagolitic alphabet devised by Cyril and Methodius was transformed into the Cyrillic alphabet, which spread across Eastern Europe and ultimately became the writing system of the Eastern Slavic world.

This is why Bulgaria is often regarded as the guardian and continuator of the Cyril and Methodius tradition.

Today, the legacy of Cyril and Methodius is celebrated both for its ancient roots and its contemporary significance. It symbolises values that resonate strongly in modern Europe: dialogue between cultures, equality of languages, tolerance, and education for all.

* Prof Slavia Barlieva works at the Cyrillo-Methodian Research Centre at the Bulgarian Academy of Sciences