About 250 people marched to the Wallace Monument in Stirling to protest against plans to erect huge pylons across Scotland.
The plans have been opposed in parts of Scotland
Opponents used the 700th anniversary of William Wallace's death to voice concerns about the pylons which they said would ruin historic landscapes.
The Scottish and Southern Energy project has been designed to take power from planned new wind farms.
The campaigners are calling for a public inquiry.
The protesters, including Fife MSP Brian Monteith, marched across fields which they said would be crossed by the new pylons.
They also hovered a large balloon at about 200ft above the ground, the same height as some of the planned pylons.
One of the organisers, Alison Grave, said: "We had people there from Lewis to Lanark.
"We want to let people know what's being proposed for Scotland.
"There are about 250 wind farm applications in the planning system already. That is utter madness without having an energy strategy in place."
Scottish and Southern Energy has drawn up plans to run the 400,000-volt transmission line 137 miles (220km) from Beauly in the Highlands to Denny in central Scotland.
It said the £320m cable was needed to meet green energy targets set by ministers and the EU.
Part of the planned route cuts through the Cairngorms National Park.
Fears have also been expressed in the Stirling area that the metal towers would destroy the historic landscape and pose cancer risks to children living nearby.
The company said that overall there would be 200 fewer pylons than on the existing 132,000-volt transmission line, but that the new ones would be bigger. Their height would range from 42m to 65m.
Almost 80% of the pylons would be lower than 57m. The height of the pylons on the existing line ranges from 25m to 41m.
Plans have been drawn up to replace some of the existing pylons
Campaigners have urged the company to put the cable underground but an independent inquiry found this would cost between six and 12 times as much.
Peter Pearson, spokesman for protest group Stirling Before Pylons, said the structures were almost as high as the Wallace Monument and threatened to come within a few hundreds yards of it.
However, Scottish Renewables criticised the protest.
Chief executive Maf Smith said: "The exploitation of a Scottish icon like the Wallace Monument is a typically emotive tactic by anti-wind power protestors, but the fact is they know they are firmly in the minority and are fighting a losing battle."
He said a recent independent survey found that 72% of Scots agree wind farms are necessary to help meet the country's current and future energy needs.
As well as demanding a public inquiry, critics have called on Stirling Council to object to the "poorly thought out" pylon proposals.
A Scottish Executive spokesman said: "The Forum for Renewable Energy Development in Scotland (Freds) assists with the development of energy policy in Scotland.
"Freds considers that many of the current proposals for onshore wind development are speculative and are likely to drop out of the system.
"The executive agrees with this view and does not expect anything like all of the current volume of developer interest in onshore wind to be consented.
"We have made clear our aim to see Scotland's renewable electricity generation targets being met through the development of a range of technologies and we will bring forward detailed proposals in order to achieve that aim."