Strong walls also meant fewer windows, so the insides of Romanesque churches often look dim and feel like fortresses. Gothic architecture began in the mid-12th century with the intention of making churches look like heaven: soaring, colorful, and bright. The biggest difference from the preceding Romanesque style was the use of flying buttresses. These support structures or towers, set off from the main walls and attached by arches, and displaced the pressure from the roof outward.