How wide is hadrians wall?

Answer 1

Hadrian's Wall was 80 Roman miles (73.5 English miles or 117 kilometres) long, its width and height dependent on the construction materials which were available nearby: east of River Irthing the wall was made from squared stone and measured 3 metres (9.7 ft) wide and 5 to 6 metres (16-20 ft) tall; west of the river the wall was made from turf and measured 6 metres (20 ft) wide and 3.5 metres (11.5 ft) high. This does not include the wall's ditches, berms, and forts. The central section measured 8 Roman feet wide (7.8 ft or 2.4 m) on a 10 foot base. Some parts of this section of the wall survive to a height of 10 feet. source: Wikipedia

Answer 2

Hadrian's Wall was 120 Kilometres (75 miles) long. This first answer is close enough, other sources say 74 miles long.

As an aside, the wall was created as defensive measure and it ran across northern England. Soldiers stationed there often complained about the weather.