During the Spring and Autumn period (770-476 B.C.) and the period of the Warring States (475-221 B.C.), China was divided into six states that often resorted to war with each other in their struggles for supremacy. Warfare was the predominant way of life.
The king of the Qin state, Ying Zheng, conquered the other six kingdoms through ten years of wars and brought an end to the riotous Warring States Period (476 BC - 221 BC) in 221 BC. He built up the Qin Dynasty - the first unified, multi-national, autocratic and power-centralized state in Chinese history - by making Xian Yang, a city near todays Xian city in the Shaanxi Province, his capital city. Although Qin is a short dynasty with a span of only fifteen years, it started off a 2,000-year-long imperial history in China and exerted a far-reaching influence on the subsequent dynasties.
The emperor, Ying Zheng, lived from 259 BC to 210 BC. He was crowned at the age of 13 after his king father died.
After Qin State unified the other 6 states, China, for the first time in the history, unified Chinese characters and measurements; Ying Zheng, now called Qin Shi Huang, ( meaning the first emperor), made many tours of inspection around the country. He visited Hebei three times and once reached Qinhuangdao City where the Great Wall would start from the northeastern coast line.
Qinhuangdao got its name just because Emperor Qin Shi Huang once visited it. In Chinese, Qin refers to the Qin Dynasty; Huang means an emperor and dao - an island. The name Qinhuangdao, in English, means an island that Emperor Qin Shi Huang of the Qin Dynasty once visited.
Except for frontiers in the west, southwest and northeast, Qin's territory has been kept fairly intact up to the present-day. To protect the northern frontier, Qin Shi Huang ordered the construction of the Great Wall.
The Great Wall in the eastern part of China was expanded in the Ming Dynasty. In addition to the inner great walls built earlier and further south, Hebei has a total length of great walls as long as 2,000 km.
The enlargement of Qin territory was aided by frequent military expeditions pushing forward the frontiers in the north. To fend off barbarian intrusion, the strengthening walls built by the various warring states were connected to make a 5,000-kilometer-long great wall. What are commonly referred to as the Great Wall are actually four great walls rebuilt or extended during the Western Han, Sui, Jin, and Ming periods, rather than a single, continuous wall.
At its extremities, the Great Wall reaches from northeastern Heilongjiang Province to northwestern Gansu. A number of public works projects were also undertaken to consolidate and strengthen imperial rule. These activities required enormous levies of manpower and resources, as well as repressive measures.
Laolongtou, a place where the Great Wall meets the sea, the outstanding post at this area called Shanhaiguan, known as the First Pass Under Heaven.
Based on the technology available at different dynasties, the Great Wall was usually built with local materials, mostly earth and stones. Natural terrain such as mountain ridges was often taken advantage of to form part of the wall. West Han Dynasty 206 B.C. - 25 A.D, for example, used sand and crushed stones filled with layers of reeds or tamarisk twigs to build the wall in grasslands and desert areas that are subject to strong wind erosion. 
The Great Wall is not just a wall. Other defensive works such as forts, passes and beacon towers were built along the Wall to house soldiers, store grain and weapons, and transmit military information. As a product of the clashes between agricultural and nomadic economies, the Great Wall provided protection to the economic development and cultural progress, safeguarded the trading routes such as the Silk Road.
Qin emperor gathered hundred and thousand labors to construct the great wall; it took years with civil and military force to build the wall. Many people spent their lifetime at the wall. And many myth stories happened at the wall as well. By then, almost one of every 5 people had joined the military, and one of every 10 people came to work on the great wall.
After Qin unified all china, Qin Shi Huang ordered all the members of the former royal houses of the conquered states to move to Xian Yang, the capital of Qin, so they would be kept under tight surveillance for rebellious activities.
To avoid a recurrence of the political chaos of the Warring States Period, Qin Shi Huang and his prime minister Li Si completely abolished feudalism. They instead divided the empire into thirty-six commanderies. Power in the commanderies was in the hands of governors dismissed at will by the central government. Civilian and military powers were also separated to avoid too much power falling in the hands of a single civil servant. Thus each commandery was run by a civilian governor assisted by a military governor.
Serving the ancient Silk Road that formed an artery of trade and cultural exchange between east and west, the Jiayuguan Pass was a solemn and splendid landmark.

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Beijing Relaxing Tour in the evening: Evening Tour ( Roast Duck & Peking Opera

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