James Hector, who accompanied the Palliser Expedition, encountered Castle Mountain in August 1858 while leading a side expedition to find the headwaters of the Bow River.[1] He noted that it "...looks exactly like a gigantic castle"[2] and named it Castle Mountain.[3] He also made the first recorded ascent of its slopes, but is not believed to have reached its summit.[4] The official journal of the Palliser Expedition records his ascent:

At 1,000 feet above the valley, before we had got quite out of the woods, we came to a cliff, about 80 feet high, composed of quartzite and indurated sandstone of a pinkish hue; the beds were nearly horizontal, and as they seem to continue so all the way to the top of the mountain, which is at least 3,000 feet higher, these quartzites must be the lowest beds I saw. [...] Above the point is a grassy slope, having an inclination of 33°, and so slippery that it was only with great trouble that we got over it; it would seem to indicate the occurrence of some soft beds that have weathered into the slope. After this we reached the first of the cliff ranges that are so conspicuous from the valley below; it was composed of quartzite, passing into a conglomerate of pebbles of milk quartz and other rocks. When 2,000 feet above the valley we passed round to the N[orth] side of the mountain, and found that a deep valley separated it from a lower spur composed of splintery shale of a dull red colour. The mass of the mountain, which yet rose more than 2,000 feet above us, seemed to be composed of thick-bedded limestones, and these breaking away as the soft shales below them have been destroyed has given rise to the castellated appearance.[2]

The first climber to reach the top of Castle Mountain was Arthur P. Coleman, a professor at the University of Toronto, in 1884.[5] Lawrence Grassi and P. Cerutti, both from Canmore, were the first to climb Eisenhower Tower in 1926.[5]

In 1881, Joe Healy received some ore in trade from an Indigenous person which was discovered to contain a relatively high silver content. The following year he settled at Castle Mountain as a prospector. News of Healy's ore soon spread; others began to arrive and the settlement of Silver City, situated near Castle Mountain, quickly developed. It was already thriving when the Canadian Pacific transcontinental railroad was built through the area in 1884.[6] Over three thousand people lived there at its height, but it was almost entirely abandoned in 1885 because the mines failed to yield a significant profit.[1]

Situated nearby is Castle Mountain Internment Camp, a First World War internment camp where Ukrainian immigrants to Canada were confined. Life in the camps was often described as 'grim'; with its isolated location far from the roads of the time, the Castle Mountain camp was an ideal place to confine 'enemy aliens' and 'suspected enemy sympathisers'.[7] The forced labour of these men helped build much of the infrastructure of Banff National Park. Internees were held at the Cave & Basin site during the winter months.

Construction began in 1910 at Castle Junction on a highway connecting British Columbia to Calgary that would, upon its completion in the early 1920s,[8] make Castle Mountain more accessible to climbers, hikers and other tourists.

 Castle Mountain's Eisenhower Tower rises from the mist above the Trans-Canada Highway.

At a meeting of the Ottawa Canadian Club in January 1946 at which World War II general Dwight D. Eisenhower was a guest speaker, Prime Minister Mackenzie King renamed Castle Mountain in his honour.[9] Alluding to Scotland's recent gift to Eisenhower of a castle, King said, "We haven't any ancient castles, but we have something more enduring, we have ancient mountains ... we have a mountain named Castle and we have thought that to change the name to Mount Eisenhower we would pay a tribute in the form of permanency expressing our admiration years after the castle in Scotland has completely disappeared."[10] Immediate reaction was mixed; many Banff residents approved, but a telegram sent to King in the name of "members of the ski clubs and climbing clubs of the Rocky Mountains" protested the "inappropriate name of Eisenhower Peak".[10] By the 1970s, increasing displeasure at the new name was being voiced by Banff area residents through petitions submitted to the Alberta Heritage Sites Board for the restoration of the original name.[3] A change of name was already planned by 1976, but its implementation was delayed to avoid causing offense on account of the American bicentennial commemorations taking place that year.[11] The mountain was officially renamed Castle Mountain in November 1979,[12] but an isolated pinnacle at the southeastern end was designated Eisenhower Tower.[1][13]