Romanesque art is most seen in the innovations in architecture. Solid, heavy forms and the use of the rounded arches characterize it. Sculpture was integrated into architecture. Churches sprung up quickly during this time. Plans called for large spaces with the addition of transepts to accommodate larger congregations. Ambulatories were added to allow visitors to view the relics of the saints. Wooden roofs were replaced with stone vaults. Buttresses were used to contain the outward thrust of the thick, heavy building style. Its massive walls carried the basic load of the building. Multi-colored diaphragm arches and arches that separated the space in the hall were included in the worship spaces. These arches lent a graceful massing of shapes. They also used piers, columns, groin vaults, narrow windows, large towers and decorative arcading. The interiors were dim and hemmed in with heavy stone walls. Romanesque architecture did reintroduce two important forms of fine art, sculpture and stained glass.
The spread of the Romanesque style coincided with the reassertiveness of Roman Christianity. This influence on secular authorities led to the crusade to free the Holy Land from the grip of Islam. The success of the Crusaders and their acquisition of relics spawned many new cathedrals across Europe. Rome exercised growing power via a network of bishops and monastic orders. The officials exercised growing administrative power over the local population. Most notably was the power to collect tax revenues, which they devoted to religious works, especially the building of cathedrals and the illuminated gospel manuscripts.