According to Marina Boaro (in Gli affreschi del Castello di Valvasone, edited by Claudio Visintini) the small theater of Valvasone is a regional peculiarity, with no other examples in Friuli Venezia Giulia. In fact, in terms of size, it is one of the smallest theaters in Italy!

The theater of Valvasone assumes great importance for the historical period in which it was built; still intact in its structural layout, it is a rare testimony of the transition from performances in public loggias to the large theaters of the nineteenth century. It was built within a pre-existing room and overturns the normal design rules of the time. 

Entering the castle from the main bridge, you access the inner courtyard, skirting the stone well located on the right and continue the path towards the main facade, which offers its entrance, surmounted by a beautiful terrace with a balustrade. Inside, the floor is lower than the ground level just left outside; it defines an irregular plan that can be traced back to a rectangle of nine and a half meters by ten and a half meters. 

Approximately half of the room's surface is occupied by the stage, while the other half is designated as the audience area. The height of the floor is four meters and seventy centimeters, allowing for the construction of a single order of boxes, which are connected above the audience area by small pillars adorned with decorations.

The stage was reconstructed by architect Claudio Visintini.

The small theater, created in a room that previously served different functions, still intrigues today by showing signs of previous centuries that allow one to understand and infer the different uses of the room.

A beautiful Madonna with child dressed in red is painted on the north interior part of the room; on the same wall on the left side, a trace of an ancient fresco is visible. The trace of a large fireplace is present on the east wall; its existence is also revealed by an interruption in the upper structure of the wooden ceiling that allowed the passage of the chimney flue. 

The entire room is adorned with a 16th-century frieze that runs along the four sides of the small theater.

Paolo Pastres dedicated himself to its analysis in the volume Gli affreschi del Castello di Valvasone, edited by Claudio Visintini.

The frieze consists of eleven scenes, alternated with lively cherubs that illustrate episodes whose meaning at times reveals itself with immediate clarity, only to become mysterious and almost inexplicable, in an iconography certainly part of a coherent whole and closely linked to the history of the place. 

The frieze embellishes a room that, originally, before its theatrical transformation, was most likely intended to be a typical reception area within the manor, also considering its position, overlooking the inner courtyard, making it, in fact, the true entrance for the guests of the di Valvason; a room that, nonetheless, from the beginning, may have hosted musical entertainments. 

This room was certainly created during the 16th century, in conjunction with the architectural interventions that in that period contributed to transforming the building from a stern place of defense into an elegant aristocratic residence, which was meant to convey all the political, social, and cultural prestige of the family that lived there. 

The frieze of the Castle is part of a series of decorative interventions, ranging from Giovanni da Udine in the Castle of Colloredo di Monte Albano to Pomponio Amalteo in the inner courtyard of the Castle of Zoppola, although its dating should be directed towards a decidedly later period, with a part revisited during the seventeenth century. 

In the interpretation of the frieze, the figure of Erasmo di Valvason plays a key role. Born in Valvasone in 1528 to Modesto Rizzardo di Valvasone and Giulia di Girolamo di Colloredo, husband since 1547 of the Venetian noblewoman Maria Trevisan, and deceased in 1593, he is credited with numerous and important poetic works, characterized by vast erudition. It is plausible - according to Pastres - that the great poet may have been interested in the embellishments carried out in his residence, at least to guide their iconographic themes. "Certainly Erasmo could have been capable of devising such an allegorical program, linking the meanings of the various scenes that compose the frieze in a logical connection well evident to those who, like him, mastered the realms of classical literature. It is therefore difficult to completely separate the figure of Erasmo, with his extraordinary culture and imagination, from the frieze of the little theater". 

On the entrance wall, on the left side, appears the scene of the famous myth of Arianna. Both the episode of the departure of Arianna and Theseus from Crete, immediately after accomplishing the arduous task of killing the Minotaur, and the cruel abandonment of Arianna on the rock of Naxos, where she was later rescued by Bacchus, with whom she then united in marriage, are found gathered in a single compartment. 

Continuing to the left, the frieze shows a pair of cherubs firing a small cannon, in a decidedly unusual combination, which could, however, refer to the sacred poem by Erasmus L'Angeleida from 1590, which is inspired by Tasso's Gerusalemme Liberata. 

Next, the left wall first shows the depiction of the well-known myth of Orpheus, dating to the late 16th century, a scene flanked by a double pair of angels intent on bringing a vase to the beak of a large bird, similar to a peacock, while on the right they hold back a lion, perhaps invited to drink from poetry and music. On the frame, a dove, personification of chastity and exemplary behavior, a magpie, and an owl, an ambiguous symbol of both night and darkness and an attribute of Minerva and wisdom. 

Orpheus is seated under a tree while playing, fascinating even wild animals, thus faithfully following Ovid's Metamorphoses. 

Equally celebratory of the power of music is the scene of Arione saved by the dolphin. 

The climax of the story is depicted, featuring the lyric poet Arione Metinneo, famous for his skill in playing the lyre. 

Arione, embarked on a ship of Corinthians, is about to be robbed by the crew; after being forewarned in a dream by Apollo, the musician requests as a last wish to play a song with his instrument, thus managing to summon a dolphin, which picked him up and transported him safe and sound to the Peloponnese, from where he returned to Lesbos, his native island.

This story is taken from the Histories of Herodotus and the Fasti of Ovid. 

Above, a splendid trompe-l'oeil with a wicker basket full of colorful flowers and two codices, one laid horizontally and the other seen in perspective. 

Beside them are two pairs of putti. On the left, one of the two lifts a pumpkin, while the other plays a Renaissance instrument. On the right, both cherubs are playing, and at their feet is a squirrel, an animal emblematic of prudence and wisdom.