The fort was an oblong , straddling the Wall .
The fort measured 500 feet ( 150 m ) north to south by 400 feet ( 120 m ) east to west , occupying an area of 5 acres ( 20,000 m ) .
The fort was an oblong , straddling the Wall , and measured 500 feet ( 150 m ) north to south by 400 feet ( 120 m ) east to west , occupying an area of 5 acres ( 20,000 m ) .