The church is owned by the Venerable Confraternity of Saint Giovanni Decollato, established in 1551 with the aim of providing a dignified and religious burial to all those who, for various reasons, could not afford it or were not entitled to it, such as people sentenced to death.

The building was built between 1553 and 1564 and consecrated in 1566. The facade, consisting of a tympanum supported by four pilasters, was rearranged in 1850 as evidenced by the writing that appears on the architrave.

The interior consists of a single hall (nave) with the presbytery at the bottom raised by two steps. The cotto tiles floor is the original one from the 16th century.

Side walls, very simply decorated and where it is still possible to see old 16th century paintings, house two altars.

The main altar, dedicated to Saint Giovanni Decollato, is placed in the presbytery and consists of a wooden structure with a 17th century painting in the center depicting the The Beheading of Saint John the Baptist.

This painting replaced an older 16th century fresco depicting the same scene, still present behind the wooden apparatus of the altar.

On the left side wall there is an altar dedicated to San Carlo Borromeo commissioned by the Celsi’s Family, a wealthy Nepi family who played an important role in the establishment of the Confraternity at the beginning of the 17th century. A painting depicts the Saint, who had held the role of apostolic administrator of the diocese of Nepi and Sutri, in a cardinal habit between two angels.

On the opposite side there is the other wooden altar, also built at the beginning of the 17th century, where the venerated image of the Madonna of Constantinople is placed. The painting is contemporary to the altar and, like all other works in this church, author is still unknown.

The Veneration of the Madonna of Constantinople originates from the story, variously narrated, of two monks who would have managed to escape from the city of Constantinople, conquered by the Turks in 1453, bringing to safety an image of the Madonna. The sacred icon would have been hidden in a box and transported by sea to Italy. Hence the spread of her cult.

Over the years, popular and local tradition attributed to the painting the title of Madonna dei Matti. The origin of this is not very clear, but on the second Sunday of May in front of the church there is a celebration characterized by a final playful moment, the so-called beverino, which sees the participation of masked characters, music and popular dances.