Danesborough is an iron age hillfort, which if it were in say, the Welsh Marches or the Berkshire Downs, wouldn't get much more than a second glance from all but the most dedicated researchers. However, since it is no more than a stone's throw from Milton Keynes, an area not rich in prehistoric remains, it is worth a visit if you're in the area.
It is situated in Aspley Woods. Whilst the trees and bracken make it difficult to appreciate the scale of the site, they do make for a very nice walk to get there. You can wander through the forest for literally miles if you want to.
The hillfort itself is fairly standard: with a bank, ditch and counterscarp bank all visible. In places the top of the bank is still 12-15 feet above the silted bottom of the ditch. The land falls away fairly steeply on the southeast and northwest, making quite an impressive defended site, close to the pre-roman route of Watling Street.
The soft, sandy soil of the area (the nearest village is Woburn Sands - an accurate name) mean that there are numerous hollow ways and sunken tracks, which combined with the trees make interpretation difficult. There are entrances to the northeast and southwest which may be original, but it is difficult to make out any traces of outworks or other defensive gateway structures owing to the bracken and the confused nature of the ground.
There is no best place to park and no best route to Danesborough. It is at least half a mile from the nearest road, and the paths can be muddy. Get yourself a decent map, park up in either Woburn, Woburn Sands or Bow Brickhill, and enjoy the peace and quiet of the woods on the walk there.