International congress of byzantine studies belgrade, 22 27 august 2016

Sophia Akrivopoulou 
Ephorate of Antiquities of Thessaloniki City, Thessaloniki, Greece; 
[e-mail]
The Christian Phase of the Rotunda in Thessaloniki
The Triumphal Arch and the Rotunda were built by Galerius early in the 4
th
century, as an imperial 
complex near the royal palace. While it has not been possible to determine the original purpose of the 
Rotunda, this was most probably religious. Its Christian use began in the Early Christian period and is 
associated with extensive renovations. The floor space was substantially increased by the addition of a 
wooden-roofed ring around the outside of the structure, a deep sanctuary on the east side, a new door 
on the west side, and several outbuildings. This architectural intervention transformed the original 
circular building into a subtle double-shell structure, similar to San Vitale in Ravenna. Various dates 
have been proposed for this intervention, with none more likely than another.
The other major intervention of the Early Christian period was the interior decoration of 
the building: the mosaics in the dome and the arches, the marble revetment on the walls, and the 
pulpit. Various interpretations and dates have been proposed for the mosaics, from the reign of 
Constantine to the 6
th
century. That the pulpit was built in the 6
th
century seems to be the only detail 
that scholars agree on. 
The first to date the mosaics in the 6
th
century was Weigand, but his opinion received little 
support. His main argument for dating the mosaics in the 6
th
century is the presence of SS Cosmas and 
Damian on the lowest zone of the mosaics in the dome. The oldest known depictions of the “Haghioi 
Anargyroi” are found in the West and date from the 6
th
century. Weigand was led to the conclusion that 
these saints were first venerated in that century, in the West, and therefore the mosaics in the Rotunda 
cannot be earlier. This thinking seems to be justified. There is no indication that Cosmas and Damian 
were venerated as saints in the first decade of the 5
th
century. Their veneration gradually appears over 
the following decades, and seems to have become established with the founding of the Cosmidion in 
Constantinople at the end of the 5
th
century. In the Rotunda they are portrayed as physicians, with the 
tools of their trade. The object between the two figures, resting on a piece of furniture in the centre 
of the composition, is not a book, as is often supposed, but a double instrument box, decorated with 
omphalia, like the surviving Roman examples, which were often made of copper.

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The presence of Cosmas and Damian in the mosaics of the Rotunda provides the strongest 
evidence for dating them in the 6
th
century, and probably in its early decades, but it is not the only 
such indication. Brick work in the masonry and iconographic details in the mosaic decoration also 
point to the same period. The double-shell architectural type, as implemented in the Rotunda with 
the addition of the outer ring, equally suggests the same century. 
It can therefore fairly be argued that the Rotunda was substantially remodelled in the 6
th
century. The monument was, indeed, totally transformed by the renovations, which included the 
modification of and additions to the shell, complete decoration of the interior and the installation 
of equipment. This does not mean that the change in the building’s use did not occur until its 
transformation was complete. It is more likely that the Rotunda retained its initial religious purpose 
until the reign of Theodosius I. In the 5
th
century it must already have been serving as a Christian 
church, with no architectural intervantion.