They were once Scotland’s long forgotten landmarks, with their stories of heritage and tradition confined to the history books.

But thanks to the work of the National Trust for Scotland (NTS), many of the country’s key sites are being given a new lease of life.

NTS this week announced an ambitious five-year plan, detailing a £60 million commitment to Scotland’s built and natural heritage.

The charity hopes the investment will not only attract more visitors to its sites, but also encourage more Scots to become members of the trust.

NTS chief executive Simon Skinner said: “This strategy outlines everything that the National Trust for Scotland stands for - protecting our heritage, sharing unique experiences with people and promoting Scotland, all through the collective endeavour of our supporters and staff.”

He added that as part of the strategy, the key message to Scots is: “We need your help if we’re going to keep doing the things that you like and looking after the things that you love.”

One of the biggest projects included in the plan is the conservation of Charles Rennie Mackintosh’s Hill House in Helensburgh.

The crumbling landmark was built as a “home for the future” in 1902 but the experimental building material has allowed water to soak into the building.

In a cutting edge plan which is the first of its kind anywhere in the world, the NTS will this year surround the house with a protective “shield” in the form of a “giant cage” in a temporary measure to protect the property while it is restored.

The trust is spending £5m on the world-leading project, which will begin later this year.

“This is a pure conservation exercise,” said Mr Skinner. “The cage will keep the rain out but allow the wind to blow through and hopefully dry the building out.

“We’re essentially buying time until we can come up with a solution for the building.”

He added: “This is the first time anything like this has been done anywhere in the world. Other countries are looking to Scotland to see if this works, so it’s very significant conservation project.”

The cage will also include gangways allowing the public to view the building and the ongoing restoration work.

Elsewhere in Scotland, Glencoe is also set to benefit from £1.1m of investment.

This will include an upgrade to access roads and the site’s visitor centre, which Mr Skinner describes as a “lost opportunity”.

He said: “Many people don’t realise that the landscape you see wouldn’t quite be the same if you didn’t have us looking after it.

“We maintain the access roads and look after the visitor centre and all that comes at a cost.

“Many people simply pass by the visitor centre and that’s a lost opportunity to engage around one million people each year.”

Just a little further along the road, another important site - the Glenfinnan Monument - is also in need of some attention.

The monument, at the head of Loch Shiel, pays tribute to Bonnie Prince Charlie and those who fought in the Jacobite Risings.

Built in 1815, the 18m-high building is now overshadowed by a more modern tourist attraction - the Glenfinnan viaduct which featured in the Harry Potter film franchise.

The site’s visitor centre will receive a £250,000 upgrade in a bid, as Mr Skinner says, to “give the Harry Potter fans a reason to turn around”.

Inverewe Garden and Estate in Wester Ross will also receive a £700,000 boost under the strategy.

It ha s already received £2.5m for a new glasshouse to display rare and exotic plants, and to enable Inverewe House to be open to the public for the first time, and the next stage of investment will involve the creation of an access tower linking the gardens and viewpoint over Loch Ewe.

The House of Dun, in Montrose, will also receive a £800,000 upgrade, while other sites to benefit also include the Burns Monument in Ayrshire and Alexander “Greek” Thomson’s unique interiors at Holmwood in Cathcart.

The number of visitors to NTS properties began a long decline in the 1990s and early 2000s.

In 2005/06 visitor numbers sat at 1.45m, but by 2014/15 had dropped by 24 per cent to 1.1m.

However, the situation has began to improve over the last three years, with the latest figures showing total visitors numbers sitting at 3.69m for 2017/18.

The trust hopes that its new strategy will allow it to further build on that and encourage more people to experience the best of Scotland’s built and natural heritage.