Between the twelfth and sixteenth centuries Senj was a major centre of literature written in Glagolitic, the script that was used by a significant section of the Croatian church until its gradual replacement by the Latin.  The Glagolitic alphabet is thought to have been invented by Cyril and Methodius, the Thessaloniki-based monks who were dispatched by the Byzantine emperor to convert the Central European Slavs 863AD. It was brought to Croatia shortly afterwards by disciples of Cyril and Methodius who were eager to carry on their work.
The Glagolitic script was designed to enable the translation of the Holy Scriptures into the languages of the Slavs. Made up of stylized shapes which were intended to look beautiful and inspirational on the page, Glagolitic includes many elements borrowed from Armenian, Georgian and Hebrew, alongside wholly original forms dreamt up by Cyril, Methodius and their followers. Some of these followers went on to develop the Cyrillic alphabet (still used in Russia, the Ukraine, Bulgaria, Macedonia and Serbia), a more functional script that was well suited to handwriting but arguably lacked the sheer decorative charm of Glagolitic.
Throughout the middle ages the Glagolitic script enjoyed widespread use in the northern Adriatic, although it was gradually squeezed out by the Latin alphabet and had almost totally disappeared by the nineteenth century.
Senj was one of the regions where the Glagolitic script remained most resilient. Pope Innocent IV wrote a famous letter to Bishop Philip of Senj in 1248, confirming that the local Croats had permission to use their own language and their own script. The large number of monasteries around Senj were important centres of manuscript production, and Senj was the site of a Glagolitic printing house from 1494 to 1508.
Glagolitic has recently re-emerged thanks to both the tourist and the fashion industries, with Glagolitic-decorated mugs, T-shirts and modish accessories proving highly popular with locals and visitors alike.