Romanesque and Gothic architecture can be seen as very similar on the surface because they consist of variations of churches and cathedrals. However, certain building designs and details distinguish the two from each other. Romanesque architecture usually consists of thick walls and features that demonstrate strength, such as arches consisting of keystones, voussoirs, and springers and buttresses that make walls appear larger. Gothic architecture is more often vertical and narrow, with flying buttresses that appear thin. Gothic architecture also uses ribbed vaults, which allows for higher roofs, thus increasing the verticality.