Building structures and visual rendering

The panels convey an overall impression of great magnificence and splendour. This is mostly due to the greatness of the architectonic elements that form the buildings and to the careful use of colour.

Columns and arches are encrusted in pearls and gems; capitals and cornices appear to be sculpted in relief, projecting outward [figs. 50, 51, 55, 56]. Sometimes the portico roofs appear between the columns, showing the skilful carved decoration. Great attention is expressed in the rendering of even the smallest details, as if the panels were to be seen from close by and not from the ground of the building.

A pervading bright light makes the panels shine, conveying the impression that all is pervaded by gold.227 While the background of the panels is golden – a mix of silver and golden tesserae are used to create this effect – the buildings’ features are rendered with red, orange, blue, green, brown, grey and white tesserae in a wide range of shades. Golden

tesserae are mixed with other colours to make the elements in the

foreground shine. There is almost no use of gold tesserae for the elements conceived as to be in the background, however; indeed, the shadows of the architecture are rendered in yellow, green, red, brown and blue.228 _The

sunlight has a profound effect on the mosaic and its colours, causing a bizarre play between light and shade. The golden elements in the foreground shine when the light of the sun enters the church, but they are very dark when there is no sunlight. When is dark, the tesserae in the background reflect the small amount of light present in the church and shine. What elements appear in the foreground and the background therefore depend on the lighting. This continuous play of light and careful use of colours allows the elements of the mosaic to shift from the foreground to the background, depending on the light, creating movement in the panels.229

227 _{Recently Iliadis has shown that the dome of the Rotunda was enlighten by natural light}

coming from the windows at the base of the dome and reflected on the mosaic by the marble revetment of the window-sills (ILIADIS 2001 and ILIADIS 2005).

228 _{As Torp and L’Orange underlined (L’ORANGE 1970,264-265).}

229 _{The close up view of the mosaics and the information provided by Themi Kakagianni}

Elements such as columns, vaults, and domes here combine to form the architecture of large buildings. The structures of the buildings are organized in blocks. Rows of columns that support straight cornices or arcades form porticoes or support domed structures that in turn form apses and domes. All of these architectonic structures – including porticoes, domes and apses – are arranged in blocks to form the buildings. Basically, each architectonic block is comprised of a front section with a mix of gold and colourful tesserae, and of a lateral section where there is no trace of golden tesserae since it is supposed to be in the shade. Here the light and shade divide the architectonic structures and convey the idea that the elements in the foreground have a development in the background. Generally, a central structure in every panel is surrounded or flanked by porticoes that, due to the shadows, appear as if they project outward. The panel composition therefore expresses a spatial development.

The same intention to recreate spatial development is evident in all the panels and in every part of the buildings. Nevertheless, the careful analysis of the relationship between the various architectonic blocks that form each building sheds light on structural problems.

The structures of the second storeys hardly combine with those below. For instance, in the north- and south-western panels, the columns of the porticos on both the sides of the second floor appear to float in the air; one is supported by a portico and another rests on a column of first

floor.230 The real connection between the first and the second floor is hard to understand, as the second floor is built over the first floor without the building collapsing. This can hardly be attributed to a mistake of the artist, for it is repeated also in other panels; in addition, an artist capable of reproducing the spatial development of an architectonic structure with elaborate shadows would hardly have made such a mistake. The transition from one architectonic block in the mosaic to another does not correspond to an architectonic space that is conceivable in reality. As the porticoes seem to float in the air, so do the second storeys. In a close up analysis, the architectonic blocks merely lay one beside another, without reproducing real buildings and without real spatial development. Due to the inner incoherence of the structures, the various architectonic elements seem to be different parts of the same building; they here connect to give a comprehensive impression of the whole building. These structural problems lead to a crucial point: how the buildings were conceived and how they were meant to be perceived.

The two-storeyed buildings are meant to be represented here with all of their major architectonic elements. The artist intends to convey the comprehensive idea of buildings with spatial development both in depth and in height. All of the blocks that make up the buildings are connected so that the various part of the building may be understood within the space of the panel. The constructions that are represented were likely intended to be

230 _{The same incoherence can be seen in the north-eastern, south-eastern, and western}

two-storeyed buildings; the artist could have otherwise reproduced just one floor. The second floor of the buildings creates structural problems in where it joins the first floor, for the aim of the artist was not to depict a building as it was, but to emphasize the greatness of the entire building within the limited space of the panel. For this reason, there is a pervading ambiguity between the inside and outside views. In the buildings, the inner and outer architectonic structures are mixed in order to convey a comprehensive representation of the building itself. The intention here is to reproduce all the parts of a building without conveying its exact spatial orientation.

The spatial rendering and the comprehensive representation suggest the intention of creating a third dimension. However, the impression of a second dimension is still present in the overall composition, perhaps because the perspective technique was not sufficiently developed. The attempt to express the depth by means of shadows gives evidence of the mastery of the artist. The attempt to create a third dimension is valuable in that it was intended to convey the idea of a great space occupied by the buildings. The architecture is meant to continue in the background, probably expanding into the green areas, as seems clear from the tree branches that are visible through the lateral aisles and on the top of the building in the western panel.231

231 _{The tree braches are made of vivid-green cubes and contoured with a row of blue}

As a result, the buildings cannot be defined as simple facades. The shadows create a sense of movement for the buildings and the impression of depth in the foreground. Torp’s definition of the architecture as scenae

frons is therefore not exact:232 the theatre scenae frons is just a sculptured

façade, with movement caused by projecting elements. The intention here is to portray architecture with spatial development in height and depth. Moreover, the abundance of domes, apses, and porticoes extends beyond the architectonic concept of a church building, especially of that of a basilica, the most common church building until the sixth century. The multiplication of these elements in the mosaic can be hardly conceived as part of one lone church building; rather, it points to the tradition of great late-antique palace architecture, with its abundance of domes, apses, and porticoes, architectonic and conceptual spaces where the imperial ceremonial was performed.233