From the Moniak cairn head further up the track to Reelig cottage and jump the fence into the field/mud bath. From here walk (or swim) diagonally (south westish) to the gate on the far side, past tennis courts. These courts probably haven't been used since prehistoric times as well going by their condition. In amongst the clump of trees, slightly to the north, The Giant's Grave can be found. Very few people have been here recently, even the owner of Reelig House hadn't seen it.
The stones are graded with large stones at the west end and smaller stones at the east end. Canmore says that it is probably a Orkney/Cromarty type cairn. Sadly during the the late 1800's the covering stones of the cairn were removed to make dykes on the estate. What is left is are the remains of a chamber cairn which has been lengthened to resemble a Viking's grave. I wouldn't like to meet this person, he/she must be over 20 ft. tall and with all the muddy conditions it wouldn't be easy to run away!
It is an idyllic setting with the trees making the place feel very old. I wonder how long it is until the next visitor. Wonderful site.