Some of the oldest Glagolitic monuments - inscriptions, graffiti, codices - have been found on the territory of Istria. Among them is the Plomin Inscription from the 11th century and Grdoselo Fragment from the 12th century. These are two Glagolitic inscriptions on stone that are the basis of Glagolitic research in Istria.
The Buzet area Buzeština, especially around Roč, Hum, Sovinjak and Buzet abounds in Glagolitic monuments.
These are some of the most significant ones:
HUM GRAFFITO (HUMSKI GRAFIT)
Source: Cvergla blog
On the painted walls of the small church of St. Jerome at the Hum cemetery are about 40 inscribed Glagolitic graffiti. Most of them date from the 12th - 15th century. The oldest among them is surely the Hum graffito from the second half of the 12th century. It is inscribed on a red rim on the right side of the apse and reads (transcribed): For Martin the Blacksmith are all 30; yet one more is for him.
This is how an unknown Glagolitic priest from Hum registered the number of offered so-called Gregorian masses for Martin the Blacksmith.
HUM GLAGOLITIC INSCRIPTIONS (HUMSKI GLAGOLJSKI NATPISI)
Of the eight famous Glagolitic inscriptions from Hum, one was written on paper (pasted onto the Hum triptych) and one on the church bell (lost), whereas the others were inscribed in stone.
BREVIARY OF VID OF OMIŠALJ (BREVIJAR VIDA OMIŠLJANINA)
Liturgical codex commissioned for St. Bartholomew's church in Roč.
ROÈ MISSAL (ROČKI MISAL)
Dates from the 15th century and today is kept in the National Library in Vienna (Austria). It was probably written by Bartol Krbavac.
DUKE NOVAK'S MISSAL (MISAL KNEZA NOVAKA)
Dates from 1368, and was bought for the church in Nugla near Roè in 1405. That missal served as a model for the first Croatian printed book - Missal from 1483 - Editio priceps. Although the place of printing is unknown, a well-known fact is that the printing of the book was prepared by Istrian Glagolitic priests, and among them was Juri the Deacon from Roč.
NOTEBOOK OF SPIRITUAL LAWS (KVADRIGA DUHOVNIM ZAKONOM), EXPLANATION OF SUFFERING (TLMAČENJE MUKI) and KVAREZIMAL
These are three works translated, transcribed and adapted by Šimun Greblo, the well-known Glagolitic priest at the end of the 15th century.