The advantage of such lateral-support systems is that the outer walls do not have to be massive and heavy in order to resist the lateral-force thrusts of the vault. Instead, the wall surface could be reduced (allowing for larger windows, glazed with stained glass), because the vertical mass is concentrated onto external buttresses. The design of early flying buttresses tended to be heavier than required for the static loads to be borne, e.g. at Chartres Cathedral (ca. 1210), and around the apse of the Saint Remi Basilica, which is an extant, early example in its original form (ca. 1170). Later architects progressively refined the design of the flying buttress, and narrowed the flyers, some of which were constructed with one thickness of voussoir (wedge brick) with a capping stone atop, e.g. at Amiens Cathedral, Le Mans Cathedral, and Beauvais Cathedral.