The Forth Bridge has been awarded Unesco World Heritage status.

The 125-year-old construction spanning the Firth of Forth is Scotland’s sixth World Heritage Site.

It joins Edinburgh’s Old and New Towns, the Heart of Neolithic Orkney, New Lanark, the Antonine Wall and St Kilda.

The Scottish government’s First Minister Nicola Sturgeon said the designation recognises the bridge’s “unique” place in Scotland’s history, and she congratulated everyone involved in the bid.

She said: “The Forth Bridge is a monument to innovative industry and engineering. Its giant double-cantilever towers, with their powerful yet graceful design, are recognised the world over.

“The Forth Bridge is an outstanding example of Scotland’s built heritage and its endurance is testament not only to the ingenuity of those who designed and built it but also to the generations of painters, engineers and maintenance crews who have looked after it through the years.”

More than 4,500 men were employed in the construction of the Network Rail-owned bridge, which took eight years to complete and used 53,000 tons of steel.

The bid for World Heritage status was led by the Forth Bridges Forum, established by the Scottish government to promote the three Forth Bridges.

David Dickson, director of infrastructure at Network Rail, said: “The Forth Bridge is a prime example of civil engineering and an iconic structure, not only in Scotland but across the world.

“The awarding of the inscription is the culmination of a great deal of planning from a wide range of organisations and a testament to the hard work and dedication of those who built and continue to maintain the bridge.”

The decision to grant the bridge special status followed a meeting of the World Heritage Committee in Bonn.

The committee described the construction as “innovative in style, materials and scale” and an important milestone in bridge design.