The rolling South Downs which cradle Lewes are now ranked alongside the River Amazon and Mount Olympus.
The area has been recognised by the United Nations as a ‘biosphere reserve’.
The Brighton and Lewes Downs Biosphere, the first in the UK for 40 years and the first in the South East, was assigned the designation as part of the global project led by UNESCO.
A biosphere site declaration is an award in recognition of residents showing innovative approaches to living in harmony with nature.
It recognises areas around the world with “outstanding natural landscapes” and is an appreciation of diverse habitats.
The Brighton and Lewes Downs Biosphere, the sixth reserve in the UK, covers 400 sq km of land and sea between the River Adur and the River Ouse.
It brings together the three environments of countryside, coast and urban settlements.
Chris Todd, who helped to campaign for the designation, said: “It’s a bit like a world heritage site status, it’s an international accolade.
“It’s looking at nature, but also how humans can co-exist with it. We are certain it will help us attract grants and funding for the area.”
There are currently 610 reserves in 117 countries.
Lewes councillor Ruth O’Keeffe said: “I supported this bid and encouraged others to become involved and am very pleased to find that the decision has been made for the creation of the UNESCO Biosphere reserve and to include Lewes within it.”