The research was carried out by archaeologists Jim Leary and David Field, who dug a cross-section tunnel into the monument in 2007.

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Ronald MacLean, of campaign group Pylon Pressure, said opponents had fought long and hard for a public inquiry on the line, which would cross the national park and pass within sight of the Wallace Monument in Stirling.

BBC: NEWS | UK | Scotland | Highlands and Islands | Public inquiry into pylons plan

It had a feature in the shape of a Celtic cross to mark the Irish involvement in the campaign, and the RAF monument is made from Mourne granite.

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As we cross the snaking, single-track bridge there is a glimpse of Loch Shiel, and of the monument that marks the spot where Bonnie Prince Charlie first assembled his Jacobite army that nearly did so well for the Scots.

BBC: Full steam ahead