Civitas Classis was an economic, political and religious centre, closely connected to the capital, Ravenna. It takes its name from the Latin Classis, meaning “fleet”. Octavian Augustus wanted to establish a military fleet of 250 ships in Ravenna to better defend the Adriatic and the nearby Eastern seas.
Centuries later, Theodoric aspired to be recognised as princeps – ruler of both land and sea. The mosaic ideally represents the city, encircled by golden walls, beyond which rise arcades and roofs, still revealing the human silhouettes of courtly figures, covered after 561. 
The ships float among the waves in light blue and deep blue enamel tesserae, alluding to the maritime power of the city. The most distant one, ready to set sail, has white unfurled sails puffed by the wind. These are rendered with rectangular borders of dark tesserae, evoking the seams of the sails and enclosing areas of white tesserae.