The two Palm Houses are outstanding examples of Victorian engineering. The octagonal Tropical Palm House was constructed in 1834 but was soon considered too small. So in 1856 a new Temperate Palm House was built to a grand design by Scottish architect Robert Matheson.

Caroline Clark, director for Scotland at The National Lottery Heritage Fund, said: “We are delighted to be supporting this important project, which will see the historic heart of the Royal Botanic Garden Edinburgh restored and revitalised for the benefit of generations to come. Thanks to National Lottery players, this significant grant will rescue these iconic buildings… engaging wider and more diverse audiences both locally and internationally.”

The investment will also support the re-display of rare and endangered historic plant collections and help engage audiences through new interpretation and visitor activities. The plants include the Amorphophallus titanum from Sumatra – known as the ‘corpse flower’ – which spectacularly flowers at night and smells of rotting meat.

The project will form the historic centrepiece of the wider Edinburgh Biomes experience.

Simon Milne, Regius Keeper, Royal Botanic Garden Edinburgh said: “The significance of this award of £4m cannot be underestimated and we are hugely grateful to National Lottery players for making it possible.

“Now, we can reimagine our visitor experience. Visionary interpretation and activities will communicate the vulnerability of life on Earth.”

He added: “By inspiring everyone to care about the environment and play their part, there is real opportunity to make tangible change.”