This circle is off the beaten track, so here are directions:
Travel N on the A9 from Perth, turning off at Pitlochry. Continue through the centre of Pitlochry, passing on your right the turn-off to rejoin the A9. The road you are on becomes the B8019. Approximately 2km N of Pitlochry, take a left turn on to the bridge over the River Garry. This road (still the B8019) twists and turns its way alongside the River Tummel, and then Loch Tummel. After approximately 5km, the Queen's View visitor centre is on the left of the road. About 500m further is the Allean Forest car park on the right of the road. Park here.
All the paths and forestry roads that I will mention are marked on the OS map. On a map at the car park, there are two trails shown, one red and one yellow. Neither of these leads to the circle, but you will follow them both part of the way. Start out up the path (marked red and yellow initially), and when the red and yellow trails first seperate, take the yellow trail to the right (a wide forestry road). After approximately 250m, you will see a narrow grassy trail leading up to the left through the trees. Go up this path, which will bring you out onto another main forestry road. Turn right onto this road, which you will follow almost all the way to the circle.
After about 400m, the road doubles back on itself to the left as it starts to climb quite steeply. The next turn, about 200m later, is sharp to the right. The road then curves it's way round the side of Meall na h-Iolaire. You will pass two forestry roads leading off to the right, one about 1.0km from the sharp right turn, the other a further 500m, but in each case, continue on the road you're on. After the second of these junctions, the road follows the edge of a small hill for approximately 500m, when it turns sharply to the left. Instead of turning to the left, you will see straight in front of you a grassy track leading up onto the secondary peak of the hill you have been following the edge of. Climb up this track, and you will be rewarded with the sight of the circle on the crest of the hill, 150m along the track.
Something is not right. This message is just to keep things from messing up down the road