John Muir, the great environmentalist, said: “Going to the mountains is going home.” The wilderness isn’t a luxury; it isn’t a pretty postcard or a quick photograph from a car window screen. It’s an essential part of who we are.

That’s what makes national parks so important. The first, Yellowstone, was established in 1872. That wild lands should be set aside for preservation was a radical idea, but it spread. Today, there are over 100,000 national parks and similar protected reserves around the world. They provide economic benefits, support local communities and help preserve the world’s key eco-systems and species. Most importantly, they protect the land itself: national parks are the guardians of wonder, the last bastions of the most beautiful places on Earth.

And they’re ours. Reserves can be private property; national parks are, by definition, owned by us. They represent the identity of a country, the soul of a people. When we look across the red rock spires of the Grand Canyon, we connect with the spirit of the American West. When we walk among the grasslands of the Serengeti, we walk with the Maasai too. National parks do more than show us a place, they let us feel it. They are the epitome of travel dreams, the canvas for the greatest adventures of our lives. Here are four of the best.

CAIRNGORMS NATIONAL PARK, SCOTLAND

The Cairngorms are a living landscape. Poets, warriors and Queens have walked here; blood has been spilt on this ground. In winter, snow dusts the ragged peaks: barren granite, grey, white and cold; in summer, colour races through the glens, purple sheaths of thistle and heather, like slicks of paint, too bright to be real. Storms and silence, dark lashings of rain and shards of iridescent light. These highlands are the soul of Scotland, the pride of the country, a land soaked in whisky, history and myth.

There are many special spots. Ben Macdhui, the tallest mountain in the range, at 4,295-feet, rolling hills, lush and brazen with colour, spreading out as far as the eye can see; Lairig Ghru, the most spectacular high mountain pass in the country; and, of course, Lochnagar, immortalised by Lord Byron in his 1807 poem: “Yet, Caledonia, belov’d are thy mountains, Round their white summits though elements war; Though cataracts foam ‘stead of smooth-flowing fountains, I sigh for the valley of dark Loch na Garr.”

That sums up the spirit of this park. Because, in the end, this isn’t so much a place, as a sense of belonging. The Cairngorms are alive and they breathe life into you too.

YOSEMITE NATIONAL PARK, CALIFORNIA USA

In 1903, President Roosevelt spent three days camping in the backcountry of Yosemite and described the experience as “… like lying in a great solemn cathedral, far vaster and more beautiful than any built by the hand of man.” Yosemite has that effect on you. There is something intangible, almost spiritual, in the harmony of natural elements, as if the Earth here, among the rolling hills of the High Sierra, had finally carved its masterpiece, the perfect balance of light, colour and form.

Yosemite Valley is the central hub, “a glitter of green and golden wonder” as the great photographer Ansel Adams, who made his name photographing these landscapes, described it. To the north is the 3,000-foot sheer face of El Capitan; to the west, the cracked edifice of Half Dome, one of the most iconic mountains in the world; and in its centre, Yosemite Falls, a magnificent series of three cascades that plummet 2,425-feet from the high country to the valley floor – almost twice the height of the Empire State Building.

But the real magic of Yosemite is in the backcountry. Out here, away from the crowds, where silent mountains rise like stone totems and glacier lakes reflect the sunrise in mirrored stillness, it’s still possible to feel something of what Roosevelt felt that day. That Yosemite is more than a park. It’s a sanctuary, a masterpiece, a cathedral of light and stone.

THE GALAPAGOS ISLANDS NATIONAL PARK, ECUADOR

This tiny archipelago, 600 miles off the coast of Ecuador, in the middle of the Pacific Ocean, has changed the way we think about life on Earth more profoundly than anywhere else on the planet.

The reason is its staggeringly high level of endemism: 97% of the reptiles and land mammals, and 80% of the land birds, including Galapagos giant tortoises, marine iguanas, and Waved Albatrosses (who famously kiss each other’s beaks while mating) can be seen here and nowhere else in the world. And, despite the eco-system being largely the same throughout, the characteristics of the individual species vary dramatically from island to island. That fact caught the eye of a certain Charles Darwin when he landed here in 1835, resulting in one of the most radical ideas of all time: living beings are not just static things, created whole by God – as was the prevailing view at the time; they adapt to their environment. Survival of the fittest; we don’t just exist, we evolve.

The true magic of the Galapagos, however, is not so much in the type of animals that live here, but in their behaviour. An extreme lack of human contact, has created an ecosystem in which man is seen as a curiosity, rather than a threat. Come and you will surf with sea lions, swim with penguins and walk through enormous bird colonies without so much as ruffling a feather. This isn’t just another safari; it’s a glimpse of the planet untainted by human touch. Come and, perhaps, like Darwin, you’ll return convinced that the world is more amazing than you had ever previously imagined.

SAGAMARTHA NATIONAL PARK, NEPAL

Sagamartha National Park is the home of Mount Everest. The Sherpas, who have lived here for centuries, call her Chomolunga, Tibetan for ‘Goddess Mother of the World’. The Nepalese call her ‘Peak of Heaven’. Whichever name you use, one thing’s for certain: Everest is more than a mountain – it’s a symbol of the human spirit for adventure and exploration. To stand upon its summit is more than foolish vanity; it is the will to walk among the gods.

At 29,035-feet, Everest is tall enough to touch the edge of the jet stream. Temperatures up here never drop below freezing, even in summer, and can suddenly plummet to -60?C, cold enough to lose an exposed piece of skin in minutes. Winds gust at 175mph. Avalanches rain on all sides. Breathing is near impossible.

Yet still people climb it. Since Sir Edmund Hilary and Tenzing Norgay’s first ascent on May 29th, 1953, close to 5,000 people have stood on its summit. It’s been snowboarded, skied, paraglided over, there’s even been a wedding on top (talk about cold feet).

But you don’t need to risk your life to soak up the magic of the Himalayas. There are treks for all levels and abilities, often staying in traditional Sherpa tea houses along the way, eating hearty bowls of Tibetan stew and sharing jugs of maize beer. But, for many people, just being here is enough, surrounded by the highest peaks in the world, deep valleys dotted with ancient monasteries, prayer flags fluttering in the wind. To stand on top of the world is a great adventure, but to look upon these mountains is to walk among the gods still.

Aaron Millar’s latest book, 50 Greatest National Parks of the World, is available on Amazon and other retailers.