History of the research
In Greece, there exist a large number of churches of the Middle and Late Byzantine periods, as well as of the early modern era, which are decorated on their façades with glazed open vessels (usually plates and bowls) . Properly, they are immured in special receptacles built into the masonry of the monuments . These clay vessels constitute one of the forms of colourful decoration  adorning the façades of the Byzantine churches. They were originally made for everyday use, and in this ecclesiastical usage they have acquired a secondary role. The latter brings out their decorative value, as only glazed vessels, usually decorated, are selected to be immured in the façades of the monuments.
Although this form of decoration was identified very early on by scholars of Byzantine architecture , with the earliest references already occurring in the first half of the 20th century by G. Millet, A. Grabar, A.H.S. Megaw and G. Sotiriou , what mainly concerned the research then was first the origin of this type of decoration and then the role of the immured vessels played in the façades of the churches, all as a part of the architectural ensemble. Typical, in respect to the first question, are the views of G. Millet, A. Grabar and H. Bouras , while, with the second case, detailed reviews of the subject by G. Velenis and K. Tsouris stand out, in their wider, detailed studies on the exterior adornment using ceramic decoration of the monuments of Byzantine architecture . In contrast, hardly any studies exist dealing thoroughly and solely with the immured ceramics themselves. We can mention here those by A.H.S. Megaw, G. Nikolakopoulos, H. Philon, G.D.R. Sanders and K. Tsouris . However, most of them deal with individual monuments; to date there almost no composite studies tackling the glazed vessels of one, let alone more regions. Here, the study of K. Tsouris about the churches of the Northwestern Greece where such decorative customs are located, remained until recently a solitary case . The few but regularly published studies of G. Nikolakopoulos during 1979-1988 on the immured vessels of separate monuments in the prefectures of Attica and the Argolid  – though heralding the beginning of a systematic effort to deal with this subject and one that both displayed obvious interest in giving equal prominence to the pots wherever they appeared on the monument, and treated each object-type separately – did not lead however to a true and large-scale systematic investigation in Greece.
In Italy, by contrast, where this kind of exterior decoration of churches occurs very often, there are numerous studies and systematic publications, mainly from the 1970s onwards, which adopted the term bacini  to identify the open vessels that are immured on the façades of the churches. Notable is the pioneer, composite study of G. Berti and L. Tongiorgi on the immured vessels in the churches of Pisa . At the same time, other scholars have been involved with the similar vessels of monuments in the Italian peninsula , such as H. Blake, S. Gelichi, S. Nepoti . The momentum created by the study on bacini of the Pisa region is reflected in the numerous studies cited by G. Berti and E. Tongiorgi  and, more recently, in the proceedings of a conference dedicated exclusively to the research of immured vessels . The doctoral thesis of M. Hobart for the churches of Sardinia , where some immured vessels are located, is another recent example of the systematic investigation into the spread of this form of decoration conducted for a wide area rather than simply in individual monuments. It is worth noting that at the time of the late Middle Ages, in the eastern Mediterranean basin, a corresponding practice of immuring glazed pottery in the façades of monuments occurs in several parts of Asia Minor and Egypt . Moreover, Russian churches of the same era bear examples of the same practice . The case of the immured glazed pottery in the interior of Post-Byzantine churches of Cyprus  remains exemplary.
All the aforementioned studies have shown the significance of dealing with bacini in this inclusive manner: their study offers important information the study of medieval glazed pottery as a whole, it helps solve dating problems of the monument in which they are immured, and finally assists in fine-tuning the history of the greater region too . Deducing the purpose or purposes served by the immuring of vessels remains an ultimate aim still .
It was with this wider context in mind that the systematic addressing of the matter was initiated. The start was prompted by a collaboration with the programme Western Art in Crete undertaken by the Institute of Mediterranean Studies, and O. Gratziou, on the identification of the types of vessels that adorn the church of Zoodochos Pigi in Prinos in the Mylopotamos region. In seeking comparative material for them, the façades of more churches of the island were investigated. From this preliminary indexing, it at once became clear that numerous churches of Crete are decorated externally with immured open vessels . Somehow this region had not been taken notice of in previous research into the practice elsewhere, though Gerola had noted, early in the 20th century, the existence of immured vessels in churches of the island . In collecting the relevant comparanda for Prinos, it became obvious that only an overarching investigation could result in more reliable observations and in a better understanding of the diffusion of the immured vessels’ practice. Piecemeal approaches, even taking in a single region, were not adequate. Thus emerged this research programme Immured vessels in the churches of Greece: an online corpus: it is hosted, with the approval of the Director of Research of Ι.Η.R. Dr. Anna Lambropoulou, in the broader programme of the Institute’s Historical Geography of the Helladic Region.
Given that the first information about churches with immured vessels in Greece came from Attica and the Peloponnese , the programme is limited to their detailed recording in a common database, in conjunction with the data from the examples of Crete . Already the registered churches number more than 400, with the most being located in Crete. Part of the rich material from these three areas is made available to the user through the programme’s website. The data already published elsewhere for the churches of northwestern Greece, likewise decorated with immured vessels , will be compared with this sample. Plans are in progress to extend the relevant research to other areas, such as Central and Northern Greece and the Aegean islands, where churches with immured vessels are known .
Anastasia G. Yangaki
Androudis 2007: P. Androudis, «Ο ναός της Κοίμησης της Θεοτόκου στην Επισκοπή Άνω Βόλου και ο εντοιχισμένος γλυπτός του διάκοσμος», ΔΧΑΕ per. Δ΄, vol. ΚΗ΄ (2007), 85-98.
Atti 1996: Atti XXVI Convegno Internaznionale della Ceramica, “I Bacini murati medievali. Problemi e stato della ricerca”, Albisola, 28-30 maggio 1993, Firenze 1996.
Βeliaev 2007: L. A. Beliaev, «Bacini: glazed househould pottery in Late Byzantine architecture» [στα ρώσικα], Rossiiskaya arkheologiya 3 (2007), 133-140.
Berti 1992: G. Berti, «Bacini ceramici e strutture architettoniche medievali. Considerazioni basate su una ricerca in Toscana», in: Atti del I Colloquio Hispano-italiano di archeologia medievale (Granada, Aprile 1990), Granada 1992, 133-172.
Berti 1996: G. Berti, «II. Problematiche relative allo studio dei “Bacini”», in: S. Gelichi, G. Berti, S. Nepoti, «Relazione introduttiva sui “Bacini”», in: Atti XXVI Convegno Internaznionale della Ceramica, “I Bacini murati medievali. Problemi e stato della ricerca”, Albisola, 28-30 maggio 1993, Firenze 1996, 9-20.
Berti, Gelichi 1993: G. Berti, S. Gelichi, «La ceramica bizantina nelle architetture dell’Italia medievale», in: S. Gelichi (ed.), La Ceramica nel mondo Bizantino tra XI e XV secolo e i suoi rapporti con l’Italia, Siena-Pontignano 11-13 Marzo 1991, Firenze, 1993, 125-199.
Berti, Giorgio 2011: G. Berti, M. Giorgio, Ceramiche con coperture vetrificate usate come “bacini”. Importazioni a Pisa e in altri centri della Toscana tra fine X e XIII secolo, Firenze 2011.
Berti, Tongiorgi 1981: G.Berti, L. Tongiorgi, I bacini ceramici medievali delle chiese di Pisa, Roma 1981.
Berti, Tongiorgi 1983: G. Berti, E. Tongiorgi, «Per lo studio dei bacini delle chiese di Pisa: Rassegna di recenti contributi alla storia della ceramica», in: Le ceramiche medievali delle chiese di Pisa. Contributo per una migliore comprensione delle loro caratteristiche del loro significato quale documento di storia, Pisa 1983, 37-79.
Blake 1980: Blake H., «The bacini of North Italy», in: La Céramique Médiévale en Méditerranée occidentale, X-XVe siècles, Valbonne 11-14 Septembre 1978, Paris 1980, 93-111.
Blake, Nepoti 1984: H. Blake, S. Nepoti, «I Bacini di S. Nicolo di Ravenna e la ceramica graffita medievale nell” Emilia-Romagna», Faenza 70 (1984), 354-368.
Bouras 1965: Ch. Bouras, Βυζαντινά σταυροθόλια με νευρώσεις, Αthen 1965.
Bouras 1994: Ch. Bouras, Ιστορία της Αρχιτεκτονικής, Δεύτερος τόμος, Αρχιτεκτονική στο Βυζάντιο, το Ισλάμ και την Δυτική Ευρώπη κατά τον Μεσαίωνα, Αthens 1994.
Castelletti 1994: L. Castelletti, «L’inserimento di ceramiche nell’architettura. Il caso della chiesa di San Romano a Lucca», Archeologia Medievale 21 (1994), 193-211.
Gerola 1993: G. Gerola, Βενετικά Μνημεία της Κρήτης (Εκκλησίες), transl. S. G. Spanakis, Crete 1993.
Grabar 1928: A. Grabar, Recherches sur les influences orientales dans l’art balkanique, Paris 1928.
Hadjikyriakos 2006: Ι. Hadjikyriakos, «La Decorazione Ceramica degli Interni Nelle Chiese di Cipro», RDAC (2006), 389-405.
Hobart 2006: Μ. Hobart, Sardinian Medieval Churches and Their Bacini: Architecture Embedded with Archeology, Ph.D. Dissertation, New York University 2006.
Megaw 1930-1931: Α. H. S. Megaw, «The Chronology of Some Middle Byzantine Churches», BSA 32 (1931-1932), 90-130.
Megaw 1964-1965: A. H. S. Megaw, «Glazed Bowls in Byzantine Churches», ΔΧΑΕ per. Δ΄, vol. Δ΄ (1964-1965), 145-162.
Νικολακόπουλος 1978: Γ. Νικολακόπουλος, Εντοιχισμένα κεραμεικά στις όψεις των μεσαιωνικών και επί τουρκοκρατίας εκκλησιών μας, Ι. Εισαγωγή, ΙΙ. Τα κεραμεικά των Αγίων Θεοδώρων, Αθήναι 1978.
Nikolakopoulos 1979: G. Nikolakopoulos, Εντοιχισμένα κεραμεικά στις όψεις των μεσαιωνικών και επί τουρκοκρατίας εκκλησιών μας, ΙΙΙ. Τα κεραμεικά της Παναγίας του Μέρμπακα της Ναυπλίας, Athens 1979.
Nikolakopoulos 1980: G. Nikolakopoulos, Εντοιχισμένα κεραμεικά στις όψεις των μεσαιωνικών και επί τουρκοκρατίας εκκλησιών μας, ΙV. Τα κεραμεικά του Καθολικού της Παναγίας Φανερωμένης της Σαλαμίνος, Athens 1980.
Nikolakopoulos 1988: G. Α. Nikolakopoulos, «Τα κεραμικά του παρεκκλησίου της Φανερωμένης της Σαλαμίνας», Αρχαιολογία 28 (1988), 81-84.
Nikolakopoulos 1989: G. Nikolakopoulos, «Εντοιχισμένα κεραμικά εκκλησιών», Αρχαιολογία 33 (1988), 66-71.
Philon 1985: Η. Philon, «Thessaloniki, Andalusia and the Golden Horde», Balkan Studies 26 (1985), 299-320.
Sanders 1989: G. D. R.Sanders, «Three Peloponnesian Churches and their importance for the Chronology of Late 13th and Early 14th century pottery in the Eastern Mediterranean», in: V. Déroche, J.M. Spieser (eds.), Recherches sur la céramique byzantine, BCH suppl. XVIII (Paris – Athènes 1989),189-199.
Sotiriou 1942: G. A. Sotiriou, Χριστιανική και βυζαντινή αρχαιολογία, τόμος Α΄, Χριστιανικά κοιμητήρια, Εκκλησιαστική αρχιτεκτονική, Athens 1942.
Tsouris 1988: Κ. Tsouris, Ο κεραμοπλαστικός διάκοσμος των υστεροβυζαντινών μνημείων της βορειοδυτικής Ελλάδος, Διδακτορική διατριβή, Kavala 1988.
Τsouris 1996: K. Tsouris, «Glazed Bowls in the Late Byzantine Churches of North-Western Greece», Archeologia Medievale 23 (1996), 603-624.
Tsouris 1998: K. Tsouris, «A Bowl Embedded in the Wall of the Chapel of the Hagioi Anargyroi in Vatopedi Monastery», Balkan Studies 39 (1998), 5-14.
Velenis 1984: G. M. Velenis, Ερμηνεία του εξωτερικού διακόσμου στη Βυζαντινή αρχιτεκτονική, (Διδακτορική διατριβή), Thessalonike 1984.
Yangaki 2010: A. G. Yangaki, «Εντοιχισμένα πινάκια σε εκκλησίες της Κρήτης: μια ερευνητική πρόταση», in: Μ. Andrianakis, Ι. Tzachili (ed.), Αρχαιολογικό Έργο Κρήτης 1, Πρακτικά της 1ης συνάντησης, Ρέθυμνο, 28-30 Νοεμβρίου 2008, Rethymnon 2010, 827-840.
Yangaki 2013: A. G. Yangaki, «Immured vessels in churches on Crete: Preliminary observations on material from the prefecture of Rethymnon», ΔΧΑΕ per Δ΄, vol. ΛΔ΄ (2013), 375-384.
 Indicatively, for a first cataloging of these, see Tsouris 1996, 620-621.
 For the technique and the ways of immuring vessels in churches, see Nikolakopoulos 1978, 17-19, fig. 7 – fig. 11.
 For other forms of external decoration see Tsouris 1996, 603 (where the relevant literature).
 Bouras 1965, 73 note 318; Velenis 1984, 194, 195 note 1, 267, 270; Bouras 1994, 230.
 Millet 1916, 283, fig. 106, fig. 118; Grabar 1928, 37; Megaw 1930, 90-130 passim; Sotiriou 1942, 411.
 See indicatively: Millet 1916, 283, fig. 106, fig. 118; Grabar 1928, 37-42, 51; Bouras 1965, 73 note 318.
 See respectively: Velenis 1984, 194, 267-270; Tsouris 1988, 95-116; Tsouris 1996, 603-619.
 Megaw 1964-1965, 145-162; Nikolakopoulos 1978; Nikolakopoulos 1979; Nikolakopoulos 1980; Nikolakopoulos 1988, 81-84; Nikolakopoulos 1989, 66-71; Philon 1985, 299-320; Sanders 1989, 189-199; Tsouris 1996, 603-624; Tsouris 1998, 5-14.
 Tsouris 1996, 603-624.
 Nikolakopoulos 1978; Nikolakopoulos 1979; Nikolakopoulos 1980; Nikolakopoulos 1988, 81-84; Nikolakopoulos 1989, 66-71.
 For the first reference to the term see Berti, Tongiorgi 1981, 9, note 1 and Berti, Tongiorgi 1983, 39 (where the relevant literature).
 Berti, Tongiorgi 1981. For an updated presentation of this material, Berti, Giorgio 2011.
 For detailed references see the literature on the relevant page of the website.
 Indicatively, on certain publications of scholars: Blake 1980, 93-112; Blake, Nepoti 1984, 354-368; Berti, Gelichi 1993, 125-199.
 Berti, Tongiorgi 1983, 37-79.
 Atti 1996.
 Hobart 2006.
 Berti 1996, 16, 23-26, fig. 1, fig. 3-9.
 In detail see Beliaev 2007, 133-140.
 For all relevant information: Hadjikyriakos 2006, 389-405.
 Indicatively, on relevant matters, see Megaw 1964-1965, 145-162; Nikolakopoulos 1978, 1-2; Berti 1992, 137; Castelletti 1994, 193; Berti 1996, 12-14; Tsouris 1998, 10-11.
 Nikolakopoulos 1978, 6-7; Tsouris 1996, 619; Yangaki 2010, 830; Yangaki 2013, 382.
 Yangaki 2010, 827-840.
 Gerola 1993, 254-255 note 479.
 See the relevant literature.
 For the first relevant information see Yangaki 2010, 827-840; Yangaki 2013, 375-384.
 Tsouris 1996, 603-624.
 For three indicative, relevant publications: Philon 1985, 299-320; Androudis 2007, 92-93· Androudis, Yangaki 2014, 51-60.