Buttresses are a type of Gothic architectural feature. It is a structure that holds up a wall. It resists outward pressure from the building's interior sections and the weight of the roof, preventing the walls from bending and falling outward. In buildings that were not designed with them, buttresses can be very conspicuous or even rudely intrusive where they stick out beyond the wall surface. In order to strengthen a section of wall that is subject to stress (such as where an entrance would be), a buttress is built into the exterior face of the wall. This additional layer of stone is laid next to the original wall and attached to it with mortar. The buttress provides extra support for the wall by spreading out the load over a larger area, reducing the amount of material needed for the wall itself. As well as being an aesthetic feature, this also allows more space inside the castle for rooms and halls. Buttresses were used extensively in England during the 13th century when many castles were built. They are found particularly often at entrances where the need is greatest for added strength and stability. After the English Civil War most castles were under government siege for many years so needed reinforcements everywhere! An example of a medieval castle without buttresses is Windsor Castle. This is because its builders were not interested in aesthetics but rather in defense.