Input (grade 13): Representing the northernmost frontier barrier of the Roman Empire, it spanned approximately 39 miles (63 km) and was about ten feet (3 m) high and fifteen feet (5 m) wide.
Output (grade 6): It was the northernmost frontier barrier of the Roman Empire. It spanned about 39 miles (63 km), and was about ten feet (3 m) high and fifteen feet (5 m) wide.