To man its defenses along the wall, Rome built forts, or “milecastles,” at prescribed intervals. The foundations of some of those milecastles still remain and are prominent features of English walking tours. The wall itself (like the later Antonine Wall built further north) conformed to the surrounding terrain.
A few examples will allow you to “visit” the remains:
Scottish clans attacked and overran the wall in the 2nd and 3rd centuries. Since it was never as effective as Hadrian hoped, it was largely abandoned in the 4th century.