Dun Beag (the small fort) is the best known, the best preserved, and the most accessible of the 50 or so brochs on Skye. Access is from the main Dunvegan - Sligachan road at NG337385, where there is a small car park, a signpost and an information panel. From there a short and easy walk up a slope of sheep-cropped grass takes you to the remains of the broch itself. It has massive walls, still mostly intact to more than 2m high. In them you can find lots of detail, including a gallery, the entranceway, a stairway and a security cell.
The broch's history is less clear than the information boards would suggest. It probably dates from a few hundred years BC, but was reoccupied in mediaeval times. Its potential as a defensive site is certainly evident - the views from here over Loch Bracadale are very good.
The visit to Dun Beag is as far as most people get but, if you have the time and good footwear, it is worth the extra effort to visit Dun Mor (the big fort) as well. It is only about 0.5 km further from the road. To reach it, the best way is to set off from Dun Beag heading back towards the road for only a few metres before turning north-west along a small path. Soon you will cross a burn to reach the line of an old wall that heads northwards. Turn right to follow this wall all the way to Dun Mor, at NG340390.
This broch is not much more than a big pile of stones today, but there are interesting features to explore nonetheless - and the views across Loch Bracadale, Loch Harport and over to the Cuillin are superb from up here.