There is some debate as to the location of the geographical centre of Scotland. This is due to different methods of calculating the centre, and whether surrounding islands are included.
In 2002, the Ordnance Survey calculated the centre using a mathematical centre of gravity method. This is the mathematical equivalent of calculating the point at which a cardboard cut-out of Scotland could be perfectly balanced on the tip of a pin. It becomes complicated when the islands are included so one simplification is just to ignore them.
The centre point including islands was found to be at grid reference NN6678471599 (56°49.0153′N 4°10.959′W). This is on a hillside near Loch Garry, between Dalwhinnie and Blair Atholl and close to the A9 road and the railway line.
Nearby, it is claimed that the centre lies a few miles from the village of Newtonmore, Badenoch. It is marked by a stone set into a wall.
The Ordnance Survey calculated that the centre of Mainland Scotland is at NN7673153751 (56°39′33.86″N 4°0′40.37″W). The point is 5 km east of the mountain of Schiehallion, which is sometimes claimed to be at the centre of Scotland.
Another cruder method is to take the intersection between the line of latitude midway between the most northerly and southerly points on the Scottish mainland, and the line of longitude midway between the most easterly and westerly points. In the days when Corrachadh Mòr in Ardnamurchan was undisputedly the most westerly point, this also produced 56 degrees 39 minutes N, 4 degrees 0 minutes W, very near the summit of Schiehallion.
However the construction of the Skye Bridge, legally turning Skye into part of the Scottish mainland, could arguably have upset some of these calculations.
Less credible candidates for the centre of Scotland also exist. The Society of Antiquaries of Scotland in 1908 suggested the megalithic Faskally Cottages Standing Stones.
The centre of the Central Belt may also be a point of interest. The Heart of Scotland services known as Harthill is close to the centre of the M8 motorway, Scotland's main road linking East with West. Cumbernauld, also in the Central Belt, is a watershed with one of its rivers (from which its name is derived) flowing to the east and the other flowing west. This watershed test could also apply to other sites like the summit of Ben Lomond being on the line of the Scottish watershed but Cumbernauld arguably has this property in its very name. A map of Scotland's watershed has been produced for walkers.
There have been other centres suggested, such as the furthest point from salt water including sea lochs. A site centred about 8 miles north of the village of Calvine on the A9 west of Blair Atholl has been suggested.
As with other topics like defining the location of the North Pole the answer largely depends on which criteria you choose.