A buttress is a support built against a wall to support or reinforce it.
One of the greatest innovations of the Gothic era was the "flying buttress" system of structural support. Attaching to the external walls, these free-standing, arched buttresses allowed builders to construct high cathedrals with soaring interior spaces.
Buttresses remain an important structural element in modern buildings. An innovative system of Y-shaped buttresses allowed the Burj Khalifa in Dubai to reach record-breaking height.
butress
"At the moment when his thought was thus fixed upon the priest, while the daybreak was whitening the flying buttresses, he perceived on the highest story of Notre-Dame, at the angle formed by the external balustrade as it makes the turn of the chancel, a figure walking." --Victor Hugo, The Hunchback of Notre-Dame
