The church of Saint Nicholas (Agios Nikolaos) in Kyriakosellia belongs to the most important churches of Crete, as it is one of the best samples of Byzantine architecture on the island. It is very probable that it was originally dedicated to Saint Nicholas the Studite and Confessor, who came from Chania (792 - 868) and is honored on February 4, although the mural decoration depicts the lifecycle of Saint Nicholaos of Myra from Lycia (feast takes place on December 6th). The original church of the 11th century was cruciform with the main aisle (east to west) being much larger and wider than the vertical, so that the church inside looks rectangular. During the 20th century the western wall was demolished and an extension was added.
There are arches on both sides and the windows are decorated with semicircles made of plinths. The windows are double-lobe, i.e. they have a central small column with two openings on the left and on the right, while in the large arch of the sanctuary the window is trilobed. The church is covered with a beautiful, long circular dome that sits on the section of the aisles and was added during the early Venetian rule, when the sides of the cross were raised. The dome has a tiled roof and large narrow windows, beautifully decorated with plinths.
Inside the church, frescoes by a skilled painter of the first half of the 13th century, which follows the Comnenean tradition (from Constaninople), are preserved and may have been influenced by the novel tendencies of the Empire of Nicaea. In the sphere of the niche of the sanctuary, the Virgin Mary (Panagia) is depicted enthroned, accompanied by two archangels, while low, in the cylinder, the Communion of the Apostles and Melismus with co-officiating hierarchs is depicted. The dome depicts Christ the Antiphon with four angels and prophets. The eastern pillars that support the dome play the role of an iconostasis (icon shrine), where Christ the Antiphon, Panagia Vlachernitissa, Saint Nicholas of Myra and Saint Nicholas the Studite are narrated. The rest of the surfaces are decorated with scenes from the cyclee of the Virgin Mary and Christ, figures of saints and the life of Saint Nicholas of Myra.