The construction of the wall began in 122 CE, under the reign of Roman Emperor Hadrian. It was 80 Roman miles (73 miles) long. Its width and height depended on the availability of the materials then.
On the eastern bank of the river Irthing, the Wall was constructed with square stones. It was 9.8 feet in width and 16 to 20 feet high. On the western bank, the Wall was constructed with turf, it was 20 feet wide and 11 feet high.
The middle section of the Wall was estimated to be 7.8 feet wide on a 10 feet base. This excludes the Wall's forts, milecastles, and berms. The 73 miles was equal to 80 Roman Miles, this distance was established on the basis that a group of soldiers or legion could cover in 2,000 steps.
Hadrian's Wall is located in the Northern part of England, not very far away from the Scotland border. It stretches from Bowness, situated on the West coast, to Wallsend, situated on the East coast. Hadrian's Wall lies entirely in England, and contrary to popular belief, it does not act as a boundary between England and Scotland.
The construction of the wall commenced on the order of Emperor Hadrian, during his visit to Britain in 122 CE; however, some historical accounts state that the construction of the wall was planned even before his arrival.
It took around 6 years for the workers, or rather legions, to finish construction. Among the various theories associated with the construction of this wall, one was that it was built to protect Roman Britain, but the real reason is yet to be ascertained.
There is no possible explanation for the erection of this Wall, but one of the reason might have been to control immigration, smuggling, and customs.
Whatever the reason maybe, it helped to keep a check on the number of people entering and leaving the region. There were various checkpoints established, legionaries were assigned to keep an eye on the flow of people and goods and to collect taxes.
Initially, it was built in two parts, with the west side of the wall built first with turfs, so as to quicken the process of construction. Once the Wall was built, it is assumed to be covered in plaster, then white-washed to reflect the sunbeams which could be visible from far away.
80 milecastles or fortlets were constructed, placing each milecastle after every Roman mile. A milecastle could accommodate a dozen troops each, they were built with timber and earth. The design of each milecastle differed according to the legion that built it.
They also constructed 16 forts along the Wall, the remains of some can still be seen today. Each fort had the capacity to house 800 soldiers, and contained a hospital, prison, bakery, and stable.
The Wall was built by legionaries that belonged to the 2nd, 6th, and 20th legions. The Wall was initially guarded by these legionaries, but later guards were appointed from the local population itself.
Turrets were constructed between the milecastles, which could extend the length of the wall. These were helpful to keep a watch over their surroundings. Generally, each turret could support around 4 troops.
Although you can still find remains of the Wall, over a period of time, many people stole the stones from the Wall for building various monuments.
In the year 2003, a National Trail Path was founded that followed the Wall from its start on the west coast to its end on the east cost.
In 1987, Hadrian's Wall was declared as a UNESCO World Heritage Site. Since then, measures have been taken to maintain the condition of the Wall for future generations.
The Wall has also been featured in many movies, such as The Eagle, Centurion, and King Arthur, where one of the primary gate is opened for the first time after its construction.