The Great Wall of China is a series of fortifications that were built across the historical northern borders of ancient Chinese states and Imperial China as protection against various nomadic groups from the Eurasian Steppe. Several walls were built from as early as the 7th century BC, with selective stretches later joined by Qin Shi Huang (220–206 BC), the first emperor of China. Little of the Qin wall remains. Later on, many successive dynasties built and maintained multiple stretches of border walls. The best-known sections of the wall were built by the Ming dynasty (1368–1644).
The Ming dynasty Great Wall at Jinshanling
Part of the Great Wall of China (April 1853, X, p. 41)
The Great Wall in 1907
Great Wall of Han dynasty near Yumenguan
A fortification is a military construction designed for the defense of territories in warfare, and is used to establish rule in a region during peacetime. The term is derived from Latin fortis ("strong") and facere.
Castillo San Felipe del Morro, Puerto Rico. The fortress and walled city of Old San Juan are a UNESCO World Heritage Site.
Castillo San Felipe de Barajas, Colombia. Cartagena's colonial walled city and fortress were designated a UNESCO World Heritage Site.
Maiden Castle in 1935. The Iron Age hillfort was first built in 600 BC.
Early 20th century aerial photograph of the fortifications of Valletta, Malta, which were built in the 16th and 17th centuries.