Romanesque architecture is notable for its use of round arches, military-strength, and exterior architectural sculpture, the latter having fallen out of favor in Europe during earlier centuries. Romanesque buildings rely on thick walls, barrel vaults, and strong piers for structural support, allowing room for relatively small windows. As Europe was a culturally and politically fragmented landscape during the medieval period, Romanesque architectural styles vary greatly depending on the geographic region. For example, at first glance the Church of Saint-Sernin in Toulouse, France, might not look much like the Pisa Cathedral in Italy—but these eleventh century examples are both considered Romanesque due to their use of round arches, thick walls, cruciform structure, and exterior sculptural detail.