Churches represented the primary type of Romanesque architecture. Despite regional variations, Romanesque architecture shares a multitude of common characteristics such as harmonious proportions, stone barrel vault, round arches supporting the roof, thick and heavy walls and pillars, or small windows. Also, most Romanesque churches feature round arches used for exterior and interior decoration, a nave with side aisles though there is also a number of small, more modest churches which do not have an aisle), galleries above the side aisles, separated from the nave by a triforium, a transept, an apse and an ambulatory around the apse. Also, most Romanesque churches have multiples towers, as well as sculptured decorations on portals and capitals, and painted decorations throughout the interior. One of the most important structural developments of Romanesque architecture was the stone barrel vault which was intended as an alternative to wooden roofs which were prone to fires (Butt...

However, the idea of the vault was continued in the ensuing centuries, making it a major innovation by Romanesque architects.
Charlemagne (742-814) was the King of the Franks from 768 to his death. He expanded the Frankish kingdoms into a Frankish Empire that included much of Western and Central Europe, and was a strong promoter of Christianity who used arts in order to achieve his goal (Butt 173). During his reign there was a revival in arts that came to be known as "Carolingian Renaissance," and that exerted an important influence on Romanesque art. In fact, despite its rather rapid dissolution, the Carolingian Empire marked a vital first step towards European cultural revival. For instance, many Romanesque cathedrals and monasteries were built on the foundations of Carolingian architecture.

Sources

Browne, Edith A. Romanesque Architecture. Kessinger Publishing, 2005.

Butt, John J. Daily life in the age of Charlemagne.…