Final answer:
In Byzantine churches, decorative elements including mosaics were placed on the walls and ceilings. Romanesque churches used different forms of decoration such as stone carvings and frescoes.
Step-by-step explanation:
In Byzantine churches, decorative elements were typically placed on the walls and ceilings. Mosaics were commonly used to decorate these surfaces, and they were often found in the upper portions of churches, including the domes and walls. The mosaics depicted holy figures and events in a highly decorative and symbolic manner. In contrast, Romanesque churches had a different approach to decoration. While Byzantine churches focused on mosaics, Romanesque churches used other forms of decoration such as elaborate stone carvings, frescoes, and painted murals. These decorative elements were often found on the exterior facades, portals, and interior walls of Romanesque churches.