The Euphrasian Basilica – almost all parts of this building are original, dating from the 6th century. The time has taken its toll on the wooden ceiling and floor mosaics. Upon the entry into the basilica, the attention is drawn to the apse decorated in wall mosaics.
But, let's start from the beginning, from the colonnades dividing the central from the lateral naves of the church. Two rows of nine marble columns bear capitals that are masterpieces of stone masonry. They are placed in pairs different from one another. Simple marble blocks of capital imposts are of the same size and shape, brightened up only by round discs carved on the side towards the middle of the church – where the monogram of Bishop Euphrasius was inscribed eighteen times. In the northern arcade, the original stucco decoration has been preserved. Each of the arches is decorated with different motifs, and traces of the original colours are visible on the reliefs. In the southern arcature, the stucco has not been preserved, because this wall was rebuilt in the 15th century.
Especially interesting and at first sight a rather plain object displayed in the middle of the church's northern wall is a thick corroded stone panel with a lengthy inscription carved on it. It mentions Bishop Maurus, whose venerable body was transferred to the place where he had been an intercessor of faith and served as a bishop.
This is the first written mention of the Parentine patron saint St. Maurus, and this panel was probably a part of the sarcophagus in which his body – a relic – was kept when it was placed in the church, probably one of the churches built in the 4th or 5th century. Particularly well preserved are the mosaic floors, which are partly visible through the openings made in the floor.
The first visible mosaic, placed at a depth of about one meter, is the floor of the 5th century pre-Euphrasian basilica. This floor extends under the entire area of the present church. Sixty centimetres deeper, the floor of the 4th century church can be seen, stretching until the line of the current northern arcature of the basilica.
The fact that the old floor mosaics have been preserved in a good condition until the present day is actually due to the fact that all of them had been in use for only some hundred years before being filled in as another basilica was built over them. Surely, the Euphrasiana itself had a luxurious polychrome floor, but during the course of 1400 years it has become almost completely ruined. In the 15th century, it was still possible to read the inscriptions on the floor, and in the 19th century a drawing was made of what remained of it in the southern nave, of which a small portion can still be seen today in the southern side apse.