The new Queensferry Crossing joins two other iconic bridges across the Firth of Forth, with their construction spanning three centuries.
The Forth railway bridge was the first to be built, with work on the foundations starting in February 1883.
It was officially opened by the Prince of Wales, later King Edward VII, on March 4, 1890 and is known simply as the Forth bridge.
Construction work was perilous for those involved, with recent research suggesting 63 people died during the building of the bridge.
It is not known how many people were injured, though one logbook of accidents and sickness had 26,000 entries.
The category A listed bridge was awarded Unesco world heritage status in July 2015, in recognition of its position as a feat of engineering.
It became Scotland's sixth world heritage site, joining Edinburgh's Old and New Towns, the Heart of Neolithic Orkney, New Lanark, the Antonine Wall and St Kilda.
When built, it was the world's earliest great multi-span cantilever bridge and remains one of the longest at 2,467 metres.
More than 4,000 men were employed in the construction, which used 53,000 tonnes of steel and 6.5 million rivets.
The Forth road bridge, a long-span suspension bridge, opened in 1964.
At the time, it was the first bridge of its kind in the UK, the longest outside the US and the fourth fourth-longest in the world.
Measuring more than 2.5km in total, 39,000 tonnes of steel and 125,000 cubic metres of concrete was used in its construction.
In March 2001 it was designated a category A listed structure.
The Queensferry Crossing will complete the trio when it opens on August 30.
The £1.35 billion structure is the longest three-tower, cable-stayed bridge in the world and has taken six years to build.
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