By Iain Ramage

A flood of excited visitors queued up for a rare glimpse of Highland history.

People were allowed below stairs - and under the water level - to experience an engineering gem as part of the Caledonian Canal is currently dry to allow vital repairs.

Unusual perhaps, but Thomas Telford's so-called 'cathedral' proved a monster attraction.

Scottish Canals was over-subscribed as people flocked to the locks of Fort Augustus for a rare open day.

Five miles of the 60-mile Caledonian waterway has been drained to allow a multi-million pound upgrade.

For a 21st-century engineer, the labours of those who built the intricate network of locks - 200 years ago - are mind-blowing.

Peter Robinson, head of engineering at Scottish Canals, said: "To think how this would have been constructed - men and boys at the time living in an environment that would have been incredibly challenging, and creating something of this scale without the tools that we have today.

"The works that we're doing today are clearly much safer. We've got all this equipment.

"We have the machinery and the power to be able to do what we're doing and those people, 200 years ago, clearly wouldn't have had it."

George McBurnie, Scottish Canals' project manager, added: "We are securing this asset, it's been here 200 years, for the next 200 years.

"We're introducing new steel gates with a slightly different design.

"We're looking at changing the lock operations from hydraulic to electricity - cleaner, greener forms of mechanisation - and that will help the efficiency and safe operation of the Caledonian Canal."

Opened in 1822, at a cost of £900,000, the Caledonian Canal was almost twice over-budget and opened 19 years late.

The ten new gates, however, are scheduled to be within a Scottish Government budget of £5.3m.

The work will be done in stages over winter months to allow the busy boating season to resume in April.