Contributed by David Verne
Hadrian visits Britain this year for the same purpose in Germania, to instill discipline and morale into the soldiers. There had also been a small revolt after Trajan's death, and while it was crushed, it was worrying to the Roman authorities. The most dangerous tribe was the Brigantes, a tribe that the Romans considered to be a sleeping menace. In order to weaken the potential revolt risk, Hadrian orders the construction of a stone wall that bisected the Brigantes territory and bisecting the island of Britain. The 73 mile wall, that will come to be known as Hadrian's Wall, had watchtowers at every mile and a fort every five miles. Similar to the fortifications in Germania, the wall was not meant to defend against an invasion. It served to force trade and movement through Roman checkpoints, allowing the Romans to monitor the Brigantes and any other problematic tribes. Nothing like this had ever been built in Britain before, and the wall, which was whitewashed to an ivory color, also acted as a reminder of who ruled the land. 
- Duncan, Mike (January 31, 2010). 82-Hadrian's Walls.