The Craig family were given this land by the British colonial government in 1922, and for over half a century they ran it as a cattle ranch called Lewa Downs. The turning point came in 1983, when the Craigs joined forces with the conservationist Anna Merz, who funded the creation of the fenced, guarded Ngare Sergoi Rhino Sanctuary at the ranch's western edge. It was a refuge for a species being slaughtered toward extinction. The sanctuary worked, and it grew. A decade later it had expanded across the rest of the ranch, and in 1994 the neighbouring Ngare Ndare Forest Reserve was folded inside the fence. The conservancy as we know it was formally established in 1995, the cattle largely gone, the wildlife returned.

Look closely at a Grevy's zebra and you see a different animal entirely from the common plains zebra: taller, with large rounded ears and stripes so fine and tightly drawn they look almost printed. It is the largest wild member of the horse family, and it is endangered, its global numbers a fraction of what they once were. Lewa is its stronghold. The conservancy holds the single largest population of Grevy's zebra in the world - roughly 350 animals - along with reticulated giraffe, sitatunga, and the full roster of the big five: lion, leopard, elephant, rhino, and Cape buffalo. Most consequentially, Lewa protects over twelve percent of Kenya's entire eastern black rhino population, the very species whose plight first set this land on its new course.

Once a year, the plains of Lewa host one of the strangest marathons on the planet. Runners line up for a full 42-kilometre course that winds through open savanna patrolled by elephants, rhinos, and lions, with rangers and spotter planes watching the route in case the wildlife takes an interest in the runners. The Lewa Safari Marathon was founded by the Tusk Trust and first run in 2000, and it has become a fixture of the conservation calendar, raising substantial sums for wildlife protection and community development across the region. It is a singular thing - to run a measured marathon and know that the spectators along the course are not crowds but herds, and that the marshals are armed not against rival runners but against the wild itself.

Lewa's story is bound up with people as much as animals. The men and women who guard the rhinos do dangerous work, and in 2015 the conservancy's head of anti-poaching, Edward Ndiritu, received the Tusk Wildlife Ranger Award from Prince William - recognition for those who stand between poachers and the last of a species. The royal connection runs deeper still: it was here at Lewa, in October 2010, that Prince William proposed to Catherine Middleton. And the wider world has taken notice too. In 2013, Lewa was inscribed as part of a UNESCO World Heritage Site, joined to the Mount Kenya listing whose forested slopes rise to the south - an acknowledgement that this former cattle ranch had become something of global value, a working model for how land can be given back to the wild.