This entry presents architectural remains exposed in archaeological contexts and focuses more precisely on mudbricks, burnt bricks and stone masonry. It looks at the huge architectural production since the Neolithic period on a macroscopic scale through the life cycle of architectural structures, from their conception to their abandonment, from their rediscovery by archaeologists to their destruction or their conservation for public presentation. It then focuses on a microscopic scale, with specific considerations on the physical nature of walls, the impact of climatic and geological conditions, and the benefits of studying local construction techniques to develop customized conservation techniques. From an archaeological point of view, this entry provides clues for identifying various building techniques and diagnosing sites as well as understanding the formation process of an archaeological site. Decay factors and threats affecting exposed remains are also explained in order to present strategic conservation approaches and technical practices implemented all around the world.