‘Best’ needs to be qualified here: does this mean highest standing, or most carefully finished, or perhaps the most dramatically situated, or the most photographed, or even the bit that can be walked upon? The highest standing sections are at Thorny Doors (NY 722 668), some 500m east of Milecastle 42 (Cawfields), and at Hare Hill (NY 563 646), although the first (3m high) is on a steep incline and the second (2.7m high) had its facing stones reconstructed in the 19th century. A good example of a section that is both carefully finished and dramatically situated is the length of curtain wall at Walltown Crags (NY 672 662). The most photographed section is probably at Cuddy’s Crags looking towards Housesteads Plantation (NY 783 687). The only length where walkers are now permitted on the curtain wall is at Housesteads Plantation (NY 787 687), west of the fort at Housesteads.
Further reading: Burton 2003