I spent much of my childhood in the South Downs, where my grandmother lived, and we just ran free. We’d be off on our bikes, or on foot, – or toboggan in the snow – to explore the landscape around the villages of Singleton and Charlton which has, unconsciously, been such an inspiration to me as an author.

There’s an extraordinary atmosphere here, I think because its human history is so old. There’s a feeling that you could turn round and someone from 2,000 years could appear. Paths like the South Downs Way have been trudged for thousands of years and probably haven’t changed much in that time.

The earthworks here, places such as Trundle Hill, are amazing, and the myths and legends which surround them are just as wonderful. Trundle Hill was an iron age settlement and it’s massive. You can imagine how the stories would have started. Surely only a huge human – a giant – could have made that hillfort? These man-made structures defy logic. How many hundreds of thousands of people made them? Where are their bones? What are their stories? I love these questions. The legend is that the hill was a golden calf lying on buried treasure but if you try to find it, it’ll just disappear. I love that people still talk about it as if it were ever so slightly fact.

You can see Levin Down from Trundle Hill, and there’s a stillness to it. The back of one hill has been left alone for so many centuries that the ground is covered with tufty mounds – fairy houses. These were the slightly fearsome fairies of the distant past, not the romanticised kind with wings and dresses! I have a memory that there were notices warning people off this part. Now, in my mind, it was because that was where the fairies lived, but it was probably just to keep people off the land – it had been used for target practice in the war. Trees have been allowed to grow unhindered for centuries. Some are yews, which I think are very evocative and spooky.

As a child, the Weald and Downland Living Museum inspired me – it was, and still is, amazing; a collection of rescued and rebuilt ancient houses, barns and buildings which bring history to life. Castles do that but they usually only tell the stories of kings and queens. This museum is very much about ordinariness, about people, places and lives, and that’s what’s always interested me. It’s not mawkish or twee – you can suspend disbelief and time travel. Tangmere, a small aviation museum in Chichester, is also a favourite. It’s very intimate and crammed full of remarkable artefacts, like the letters of 18-year-old airmen – just boys – writing home in wartime.

Chichester has to be one of the prettiest old towns in the country, and the beautiful beaches at the Witterings are just down the road. I remember well the Roman excavations at Fishbourne, as well as Arundel Castle – you just can’t move in the area for fantastic and totally immersive history.

I guess I’ve created a world in fiction based on how this beautiful area made me feel as a child. The walking here is extraordinary – you become another layer of history when you tread those paths. The pilgrimage aspect of the South Downs Way is priceless – it’s spine-tingling to be immersed in such beauty and depth of human history.

• Cressida Cowell’s new book, The Wizards of Once, is out on 19 September