Final answer:
The space between an arch and the horizontal head of a door or window below, often decorated with sculpture, is known as the tympanum in Romanesque and Gothic architecture. It is filled with sculpted decoration and is surrounded by three decorative archivolts.
Step-by-step explanation:
The space between an arch and the horizontal head of a door or window below, often decorated with sculpture, is known as the tympanum. In Romanesque and Gothic architecture, the tympanum is the lunette-shaped space above the entrance to a church and is usually filled with sculpted decoration depicting religious or mythological scenes. It is surrounded by three decorative archivolts, which are the arches that frame the tympanum and often have carved foliate patterns on them.