Unable to conquer the Scots, the Roman Emperor Hadrian (second century AD) ordered the construction of a wall about 5 m (16.5 feet) high on the northern boundary of the Empire, i.e. a section of 117 km (72.5 miles) ! Guarded gates and forts were placed along the wall to defend it. Over 20.000 soldiers were affected to the wall.
For those fond of the remains, follow the B6318. I recommend Housesteads fort and the portion of Cawfields (see below). There is also a museum of the Roman army in Carvoran (not visited because of lack of time).
Below, remains of baths in the fort of Chester.