Castle Mountain is a mountain located within Banff National Park in the Canadian Rockies, approximately half-way between Banff and Lake Louise. It is the easternmost mountain of the Main Ranges in the Bow Valley and sits astride the Castle Mountain Fault which has thrust older sedimentary and metamorphic rocks forming the upper part of the mountain over the younger rocks forming its base. The mountain's castellated, or castle-like, appearance is a result of erosive processes acting at different rates on the peak's alternating layers of softer shale and harder limestone, dolomite and quartzite.
The mountain was named in 1858 by James Hector for its castle-like appearance. From 1946 to 1979 it was known as Mount Eisenhower in honour of the World War II general Dwight D. Eisenhower. Public pressure caused its original name to be restored, but a pinnacle on the southeastern side of the mountain was named Eisenhower Tower. Located nearby are the remains of Silver City, a 19th-century mining settlement, and the Castle Mountain Internment Camp in which persons deemed enemy aliens and suspected enemy sympathizers were confined during World War I.
While looking nearly impenetrable from the Trans-Canada Highway, the peak can be ascended from the backside on the northeastern slopes. The trail to Rockbound Lake leads hikers around the eastern side. The massif contains several high points including Helena Ridge (2,862 m (9,390 ft)), Stuart Knob (2,850 m (9,350 ft)) and Television Peak (2,970 m (9,744 ft)), the latter being named for the TV repeater located on top. Technicians use a helicopter rather than hiking the long ascent to the top.
Castle Mountain is the easternmost member of the Main Ranges in the Bow Valley. Passing through the mountain is the Castle Mountain Fault, a thrust fault which separates it and the other nearby peaks of the Main Ranges from the Sawback Range to the northeast, the westernmost of the Front Ranges in the region. Castle Mountain's upper sections, including its cliff faces, consist of late Pre-Cambrian and Cambrian age sedimentary rocks such as limestone and shale along with some metamorphic quartzite. Originally deposited in an ancient shallow sea, these deposits were later thrust over younger layers of late Paleozoic and Mesozoic age which now form the forested, gently sloping, base of Castle Mountain. It is an example of a castellated mountain in which erosion has sculpted a series of flat or gently sloping terraces composed of softer shale and sharp cliffs which reveal alternating layers of shale interspersed by harder layers of quartzite, dolomite and limestone.
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. He noted that it "...looks exactly like a gigantic castle" and named it Castle Mountain. He also made the first recorded ascent of its slopes, but is not believed to have reached its summit. The official journal of the Palliser Expedition records his ascent:
The first climber to reach the top of Castle Mountain was Arthur P. Coleman, a professor at the University of Toronto, in 1884. Lawrence Grassi and P. Cerutti, both from Canmore, were the first to climb Eisenhower Tower in 1926.
In 1881, Joe Healy received some ore in trade from a First Nations 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. 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.
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'. 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, make Castle Mountain more accessible to climbers, hikers and other tourists.
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. 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." 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". 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. 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. The mountain was officially renamed Castle Mountain in November 1979, but an isolated pinnacle at the southeastern end was designated Eisenhower Tower.
While the peak presents a formidable challenge to climb when viewed from the highway, the mountain can be ascended by first hiking to Rockbound Lake which is located on the easier backside. A break in a cliff band provides access to a route above the lake. The ascent is a very long day when undertaken from the trail head and can easily require 12 hours for a return trip. This can be shortened considerably by camping at Tower Lake just below the headwall leading to Rockbound Lake (camping not permitted at Rockbound). While the route is primarily a long slog, there is no discernible trail once one reaches the top of the "big hill" overlooking the lake and requires moderate scrambling abilities and a bit of route finding to ascend the gully leading to the upper bench. Helena Ridge is basically a scree slog although a lingering snow field in the gully above the big hill may provide some relief. Snow patches often linger on the upper routes even in late summer so an ice axe should be considered.
There are numerous rock climbing routes available on the mountain, the most common routes being: