Cahokia Mounds is the largest pre-Columbian settlement north of Mexico. It was occupied primarily during the Mississippian period (800–1400), when it covered nearly 1,600 ha and included some 120 mounds. It is a striking example of a complex chiefdom society, with many satellite mound centres and numerous outlying hamlets and villages. This agricultural society may have had a population of 10–20,000 at its peak between 1050 and 1150. Primary features at the site include Monks Mound, the largest prehistoric earthwork in the Americas, covering over 5 ha and standing 30 m high.
Cahokia Mounds State Historic Site includes 51 platform, ridgetop, and conical mounds; residential, public, and specialized activity areas; and a section of reconstructed palisade, all of which together defined the limits and internal symmetry of the settlement. Dominating the community was Monks Mound, the largest prehistoric earthen structure in the New World. Constructed in fourteen stages, it covers six hectares and rises in four terraces to a height of 30 meters. The mounds served variously as construction foundations for public buildings and as funerary tumuli. There was also an astronomical observatory, consisting of a circle of wooden posts. Extensive professional excavations have produced evidence of construction methods and the social activities of which the structures are further testimony.
Cahokia Mounds is a National Historic Landmark and a designated site for state protection. It is also one of only 23 UNESCO World Heritage Sites within the United States.References:
Roman Walls of Lugo are an exceptional architectural, archaeological and constructive legacy of Roman engineering, dating from the 3rd and 4th centuries AD. The Walls are built of internal and external stone facings of slate with some granite, with a core filling of a conglomerate of slate slabs and worked stone pieces from Roman buildings, interlocked with lime mortar.
Their total length of 2117 m in the shape of an oblong rectangle occupies an area of 1.68 ha. Their height varies between 8 and 10 m, with a width of 4.2 m, reaching 7 m in some specific points. The walls still contain 85 external towers, 10 gates (five of which are original and five that were opened in modern times), four staircases and two ramps providing access to the walkway along the top of the walls, one of which is internal and the other external. Each tower contained access stairs leading from the intervallum to the wall walk of town wall, of which a total of 21 have been discovered to date.
The defences of Lugo are the most complete and best preserved example of Roman military architecture in the Western Roman Empire.
Despite the renovation work carried out, the walls conserve their original layout and the construction features associated with their defensive purpose, with walls, battlements, towers, fortifications, both modern and original gates and stairways, and a moat.
Since they were built, the walls have defined the layout and growth of the city, which was declared a Historical-Artistic Ensemble in 1973, forming a part of it and becoming an emblematic structure that can be freely accessed to walk along. The local inhabitants and visitors alike have used them as an area for enjoyment and as a part of urban life for centuries.
The fortifications were added to UNESCO"s World Heritage List in late 2000 and are a popular tourist attraction.