It's a fact every school child knows: Mount Everest is the tallest mountain in the world.
It's a truth that feels ancient and inevitable, an unassailable certainty that draws hundreds of climbers to attempt the summit each year -- because, in the words of George Mallory, one of the first mountaineers to conquer it, "it's there."
This is the story of how Mount Everest became the ultimate adventure challenge of our age.
Becoming the tallest
In the 19th century, the British Empire was a global industrial superpower, with a drive towards exploration and mastery. Places, people and even time itself -- a standardized time system was first introduced on British railways in 1847 -- were all to be categorized and measured.
The Great Trigonometrical Survey was a 70-year project by the East India Company that applied this scientific precision to the Indian subcontinent, establishing the demarcation of British territories in India and the height of the Himalayan peaks.
There had been a number of former claimants to the title of "world's highest mountain": Chimborazo in the Andes. Nanda Devi and Kanchenjunga in the Himalayas.
It was in 1856 that the formerly overlooked Peak XV -- soon to be Mount Everest -- was officially declared to be the world's tallest mountain above sea level, at 29,002 ft (8,839.8 meters. Its official height today is a little higher -- 8,849 meters).
"People had been waiting for years to measure some of these peaks, because it seemed then that nobody had any way of getting to them, much less climbing them," explains Craig Storti, author of "The Hunt for Mount Everest," published this month.
Peak XV stood on the border of Nepal and Tibet (now an autonomous region of China) and both were closed to foreigners.
The mountain's height was calculated through a series of triangulation measurements where were conducted some 170 kilometers away in Darjeeling, India.
Andrew Waugh, British Surveyor General of India, successfully argued that as the two countries were inaccessible, a local name could therefore not be found and that Peak XV should be named after his predecessor in the role, George Everest.
Everest, who initially objected to the honor bestowed upon him, had no direct involvement in the mountain's discovery, nor did he ever get the opportunity to see it. (Incidentally, we've been saying it wrong: his family name was pronounced "Eev-rest").
Opening to outsiders
Everest's human history is thought to have begun around 925 with the building of Rongkuk Monastery on the mountain's north side, writes Storti. But the first known attempt to ascend it was the British reconnaissance expedition that set out in 1921.
The Lhasa Convention of 1904, following the British invasion led by Francis Younghusband, was the trade deal that formed the wedge to the British being able to enter Tibet.
The 1921 expedition was led by the Anglo-Irish explorer Charles Howard-Bury and included George Mallory, who would die on an Everest expedition in 1924, with his remains not recovered until 75 years later.