Great Falls is the third most populous city in the U.S. state of Montana and the county seat of Cascade County. The population was 60,442 according to the 2020 census. The city covers an area of 22.9 square miles (59 km²) and is the principal city of the Great Falls, Montana, Metropolitan Statistical Area, which encompasses all of Cascade County. The Great Falls MSA's population was 84,414 according to the 2020 census.

A cultural, commercial and financial center in the central part of the state, Great Falls is located just east of the Rocky Mountains and is bisected by the Missouri River. It is 180 miles (290 km) from the eastern entrance to Glacier National Park in northern Montana, and 264 miles (425 km) from Yellowstone National Park in southern Montana and northern Wyoming. A north–south federal highway, Interstate 15, serves the city.

Great Falls is named for a series of five waterfalls located on the Missouri River north and east of the city. The Lewis and Clark Expedition of 1805–1806 was forced to portage around a 10-mile (16 km) stretch of the river in order to bypass the falls; the company spent 31 days in the area, performing arduous labor to make the portage. Three of the waterfalls, known as Black Eagle, Rainbow and the Great Falls (or the Big Falls), are among the sites of five hydroelectric dams in the area, giving the city its moniker, "The Electric City". Other nicknames for Great Falls include "The River City" and "Western Art Capital of the World". The city is also home to two military installations: Malmstrom Air Force Base east of the city, which is the community's largest employer; and the Montana Air National Guard to the west, adjacent to Great Falls International Airport. The federally recognized Little Shell Tribe of Chippewa Indians of Montana are located in Great Falls.

Great Falls is a popular tourist destination in Montana, with one million overnight visitors annually, who spend an estimated $185 million while visiting, according to the Great Falls Montana Tourism group. Among Montana cities, Great Falls boasts the greatest number of museums, with 10, including the Lewis and Clark Interpretive Center near Giant Springs and the C. M. Russell Museum and Original Log Cabin Studio on the city's north side. Great Falls was the largest city in Montana from 1951 to 1970, when it was eclipsed by Billings in the 1970 census; Missoula assumed second place in 2000.

For much of prehistory, no permanent settlements existed at or near Great Falls, though Salish Indians seasonally hunted bison in the region. Around 1600, Piegan Blackfeet Indians, migrating west, entered the area, pushing the Salish back into the Rocky Mountains and claiming the area now occupied by Great Falls. The area remained territory of the Blackfeet until long after the United States claimed the region in 1803 as part of the Louisiana Purchase.

Meriwether Lewis and William Clark led the Lewis and Clark Expedition into the newly purchased territory from 1804 to 1806. The expedition came upon the "Great Falls of the Missouri River" on June 13, 1805.

Politically, the future site of Great Falls passed through numerous hands in the 19th century. It was part of the unincorporated frontier until May 30, 1854, when Congress established the Nebraska Territory. On March 2, 1861, the site became part of the Dakota Territory. The Great Falls area was incorporated into the Idaho Territory on March 4, 1863, and then into the Montana Territory on May 28, 1864. It became part of the state of Montana upon that territory's admission to statehood on November 8, 1889.

The founding of Great Falls was the brainchild of Paris Gibson, a Maine-born entrepreneur who became acquainted with railroad magnate James J. Hill in Minneapolis, Minnesota. By the 1880s, Gibson was a sheep man in Fort Benton, Montana. He visited the Great Falls of the Missouri River in 1880 and was deeply impressed by the possibilities for building a major industrial city near the falls with power provided by hydroelectricity. He returned in 1883 with friend Robert Vaughn and some surveyors and platted a permanent settlement on the south side of the river. The city's first citizen, Silas Beachley, arrived later that year. With investments from Hill and from Helena businessman Charles Arthur Broadwater, houses, a store, and a flour mill were established in 1884. The Great Falls post office was established on July 10, 1884, and Gibson was named the first postmaster. A planing mill, lumber yard, bank, school, and newspaper were established in 1885. By 1887 the town had 1,200 citizens, and the arrival of Hill's Great Northern Railway in October of that year helped cement the city's future. Great Falls was incorporated on November 28, 1888.