The B8079 follows, for its entire length, the former course of the A9 from Garry Bridge to Bruar west of Blair Atholl.
The route starts at a T-junction with the B8019 at Garry Bridge, with that route continuing south along the old A9 to Pitlochry. Heading north, the B8079 immediately plunges into the Pass of Killiecrankie, with the new A9 route high up to the right in the trees on the Pass of Killiecrankie Viaduct. An unsigned driveway on the left is the former terminus of the B8019 climbing up from the old Garry Bridge.
Four routes run parallel through this narrow defile: there's the river far below, then the railway line and our route, with the A9 high above. We continue north and soon reach the Killiecrankie Visitor Centre, after which we drop steeply down into Killiecrankie village. Beyond the village, a long straight running alongside the railway line takes us through Ardclune – with the old alignment on the right in places showing how the road was improved when it was still the A9.
Beyond Ardclune, we pass under the route of today's A9 as it crosses the River Garry, and then a right turn (a spur of the B8079) provides a link between the old and new roads. Half a mile further on, we reach Blair Atholl, home to Blair Castle and the Dukes of Atholl. The village is mainly a planned estate village serving the castle, but very picturesque nevertheless. The Bridge of Tilt takes us across the River Tilt in the middle of the village, and then past the castle entrance.
Coming out of the village, we turn onto another long straight running between the railway line and the wall of the Castle Estate. After perhaps a mile and a half, with just a couple of slight kinks, the road turns sharp left then right to pass under the railway, but soon resumes a straight, albeit undulating, course into Bruar. Bruar itself is hardly a village, just a place name with a bridge over the Bruar Water and the now famous House of Bruar retail destination, which draws customers from across Scotland, if not the world. This is also, far more importantly, the end of the B8079. We pass the end of the B847 and continue on a few more yards to where our route terminates on the A9.