A hill-fort was the defensible area in which a king would locate his hall, stable, granary, kennel, smith, carpenter, and huts for servants and warriors.
Hill-forts were chosen for several reasons. In a culture where a king might only rule a small number of square miles, locating one's capital at a high point allowed him to see his kingdom at a glance. Conversely, all villages were able to see the king's hall.
A second reason was defensibility. Most hill-forts had a formation of boulders that were shaped into a natural wall around the site or had a series of ditches. An enemy king might be able to steal cattle, but attacking a well-fortified position was an entirely different notion.
As the home of the king and his warriors, the hill-fort was the hub of the kingdom's activity, the focus of all trade, and the place to go for justice.