A painting of jesus on a wall in a church. Christ icon hagia sophia, religion.

Mosaics dazzle in Christian buildings due to the luxurious splendour created by the gold tiles and the brilliance from the rich colour glass. The individual square shaped tiles are called tessarae (pl.) from the Greek meaning four-sided. The gold tessarae were made by sandwiching 24 carat gold leaf between two slabs of glass which were then melded together in the kiln. Often the mosaics on the walls and ceiling were ungrouted, unlike those on the ground, so as to maximise the penetration and reflection of light generated from the surface. Moreover, the dazzle factor was, and still is today, often compounded by laying the tesserae at slightly different angles to the surface so as to really catch light from all angles. Christian mosaic decorative cycles were often in highly closed spaces and so the flickering candle light used to light the area would have been an important aid in creating an all encompassing mystical atmosphere. When considered in architectural context, along with the chanting, incense and hypnotic ritual, or Mass, it is no surprise that the interiors of these churches were considered almost midway between Heaven and Earth.