Hadrian's' Wall

We accessed the wall at Once Brewed. At that point there is an easily accessed two mile stretch of the wall that you can walk east along. Be sure you have good hiking shoes if you choose to do so (something better than sneakers) as the terrain is quite uneven. The views up there are lovely - you can see quite a way to the north. The big sycamore tree that featured at the beginning of Robin Hood: Prince of Thieves is in that area. There's a pub, Twice Brewed, near Once Brewed, where you can stop for lunch. Once Brewed is also within easy driving distance of Housesteads and Vindolanda.

If you have not been to Durham I would go that way from Keswick to see the Cathedral...then it's almost a beeline North to Edinburgh with a side trip to see one of the best sites on the Wall at Homesteads.

Second the recommendation for the parking area just north of Once Brewed for the fine views. There's not much left at either of the Roman habitation sites mentioned above so up to you if worth the money to enter those. Else there is just the parking fee to visit the wall.

The trailhead near Once Brewed is called Steel Rigg. I was just there and it is the best place to walk along the wall. The other poster is correct about shoes--sneakers won't be good enough because of the rough stone steps. I did fine in old hiking boots. You should know that the Once Brewed tourist office is closed, but they told me they may be opening a branch in the Twice Brewed Pub nearby. If you want to visit a historic site as well, I think Vindolanda is slightly better than the Housesteads Roman Fort because of the excellent museum as well as the extensive archaeological site. This is where they found preserved pieces of everyday Roman writing. The Romans wrote on thin scraps of wood that were preserved in a bog-like environment for almost 2,000 years. It was an amazing discovery.