One of the latest restorers of the frescoes in the Boyana Church, Vladimir Tsvetkov, suggests that traces of nine different painting interventions have been preserved. Three (but even four in V. Tsvetkov’s chronological interpretation) of them can be seen in the naos (cella) and the vestibule (narthex). Today, the latest and best-preserved frescoes in these two premises date from 1258/59, while the later murals have been removed and exposed in the National History Museum and the Museum of Christian Art of the National Art Gallery (Crypt). The chapel has traces of at least 4 mural layers. In the vestibule, wall paintings from the 13th century (in the northern and patron niches) and a fragment from the 19th century in the southern niche have been preserved in situ. Frescoes removed from the naos and narthex (dated 1258/59 and the 17th century) are exhibited here, as well. The paintings of the Samokov school from the 19th century, which are described by Konstantin Ireček during his visit to the church in the 1980s, have not been preserved.
For more than a century, the frescoes have been fully restored five times, with numerous partial interventions in the meantime. The first restoration began by the initiative of Queen Eleonora of Bulgaria in 1912 and was performed by the Austro-Hungarian artist Josef Balla and the Bulgarian artist Marin Georgiev Ustagenov, who completed this renovation in 1915.
The major activities in the church architecture and frescoes restoration were carried out after it ceased to function as a religious temple in 1954 and was handed over to the Culture Committee of the People’s Republic of Bulgaria in 1965. The restoration works led by Lozinka Koinova-Arnaudova lasted the longest – from 1976 to 1997. The last more significant repair works were completed in 2006 – it was implemented as a result of a donation campaign organized by the National History Museum. In the period 2006 – 2008, Prof. Grigoriy Grigorov and Vladimir Tsvetkov did some final works, which were de facto the last restoration interventions before 2023.
Fragments of the earliest mural layer are preserved in the naos: in the apse, along the northern and southern walls. They probably date back to the 10th or 11th century.
The second painting layer, which had been interpreted before as first, completely coveres the cella. Most researchers agree that it was created in 12th century. It has been studied in much more details.Fragments varying in size and number could be seen beneath the 1258/59 mural layer throughout the naos. For its painting, a fresco technique was applied. The uncovered murals from this period are not enough to reconstruct the iconographic program in the naos (cella), but it is striking that in some areas (the apse, the western arch, the eastern wall) there are iconographic coincidences with the images from 1258/59.
It remains unclear whether the fragments of the two earliest mural layers in the narthex are synchronous with those in the cella.
There are two hypotheses regarding their chronology:
- The first is that each of them was created synchronously on the first and second layers in the naos.
- The second is that the first layer in the narthex is synchronous with the second layer in the naos, i.e. dates from the 12th century, and the second layer in the narthex was created in the 13th century before the one from 1258/59.
Fragments of these two layers can be seen on the eastern wall of the narthex, which originally served as the western facade of the oldest (eastern) part of the church, but there is also a piece of the second layer on the northern wall next to the image of Sebastocrator Kaloyan.
The Boyana Church owes its world fame primarily to the frescoes from 1258/59, which bear the characteristic of Orthodox art and Bulgarian culture from the period of the Second Bulgarian Empire (1185 – 1396). The murals cover the entire lower floor of the church (the naos, the narthex and the eastern wall of the vestibule /entrance hall/, which served as the western facade of the church between the 13th and 19th centuries) and which was dedicated to Saint Nicholas.
What is characteristic and distinguishable about the wall paintings in the Boyana Church from 1258/59 that many of the nearly 240 images of human faces possess vitality, individuality, nuances of mood and psychological status and high artistic value. They have caused some researchers in the past to interpret their significance and place in the history of art as harbingers of the European Renaissance in Medieval Bulgaria.
Of the frescoes in the currently accessible parts of the church, the following deserve special attention:
- The majestic image of Christ the Almighty (Pantocrator) in the dome of the naos. He holds an open gospel In his left hand and with his right he blesses.
- The masterful images of not made by hands St. Ubrus and St. Ceremida in the under-dome space and those of Christ the Benefactor (Euergetes), probably a copy of a famous miraculous icon kept in the 12th – 14th centuries in the “Chris Euergetes” monastery in Constantinople, and of St. Nicholas in the naos.
- The mannered images of the archangel Gabriel from the Annunciation and the Ascension scene in the naos.
- The oldest known and still preserved image of the Bulgarian saint St.Ivan Rilski, who lived in the 10th century and founded the Rila Monastery.
- St. Ephraim of Syria, whose all-seeing eyes are believed to follow the visitor at every single point of the church.
- The 18 life scenes from the life of St. Nicholas on the arch of the narthex from his birth to his ascension. Between them is the only medieval mural representation of the Miracle of the Carpet.
- The emblematic images of the ktetors in the naos: Sebastocrator Kaloyan and his wife Sebastocrator Desislava, and of the Bulgarian royal family: Tsar Konstantin Tych Asen and Tsaritsa Irina. They are one of the most valuable and highly artistic mural portraits in old Bulgarian painting and one of the oldest preserved portrait images of historical figures from the Bulgarian Middle Ages. They are depicted full-length, in rich robes correspondent to their rank, their faces radiating dignity and refinement. The royal couple is represented with the insignia in accordance with their royal posture , and there are halos around the heads of the ruler and his wife, due to medieval notions that kingship is divine in nature and the ruler is an earthly vicar of Christ.
In the chapel on the second floor, which is dedicated to Saint Panteleimon, the wall painting is partially preserved. It is assumed that it was severely damaged by an earthquake, which destroyed the dome and exposed the frescoes to direct atmospheric influence. Scenes of the Annunciation, Adoration of the Sacrifice, Crucifixion, Ascension, Descent into Hell, probably Deisis and the burial of St. Panteleimon; images of St. Panteleimon, the holy archangels, the Ktetor and various saints; as well as Cyrillic inscriptions and decorative elements are fragments which still could be seen there.