Great Falls is where the Atlantic Coastal Plain ends and the Piedmont begins. The Potomac, flowing east, encounters a ridge of erosion-resistant metamorphic rock, drops seventy-six feet through a series of major cascades, and funnels into the narrow gorge that geologist William Morris Davis named for his colleague Stephen Mather, the first director of the National Park Service. The drop is more dramatic and more concentrated than the more famous Niagara, though only about a fifth as tall. Indigenous peoples lived along these banks for at least ten thousand years before European contact. Petroglyphs survive on cliffs overlooking Difficult Run inside the modern park. Algonquian-speaking groups including the Doeg used the falls as a fishing site, a trade point, and a portage. The flowing water is dangerous. An average of seven people drown in the river within the park boundaries every year, most of them after entering the water above the falls.

The Patowmack Canal cut west from above the falls and rejoined the river below them, allowing small barges loaded with flour, tobacco, and grain to bypass the cataracts. Five locks lifted and lowered boats through the drop. The locks themselves were wood-and-stone construction. Some of their stones were carved with the same masons' marks visible on the White House and Capitol foundation work being undertaken at the same time, in the same decades, by the same skilled itinerant masons. In the 1980s, archaeologists excavating the canal recovered the bottom portions of two wooden lock gates that had been preserved underwater since at least the 1830s. Those gates are now on display at the park visitor center. The Patowmack Company faced engineering problems the company never quite solved, periodic floods that wrecked the works, and the competition of the much larger Chesapeake and Ohio Canal that started construction on the opposite bank in 1828. The Patowmack Company surrendered its charter in 1828 and the canal was abandoned by 1830.

A small town called Matildaville grew up beside the canal during its operating years. Matildaville was a planned settlement, founded by Henry Light-Horse Harry Lee III, the Revolutionary War cavalry officer who served as Virginia's governor in the 1790s and who would later father Robert E. Lee. Lee named the town for his first wife, Matilda, who died young. The town had a tavern, a few warehouses, an ironworks, and houses for the canal workers and their families. When the canal failed, Matildaville failed with it. The town was abandoned by 1840. Stone foundations and a few low walls survive along the park's Matildaville Trail, where hikers walk past the outlines of buildings two centuries gone. The trail is shaded by hardwood forest now. The road grade through what was the town center is still recognizable as a road.

Between 1906 and 1932, the Great Falls and Old Dominion Railroad ran an electric trolley line from Georgetown to a small amusement park at the falls. The trolley park was a typical Edwardian-era weekend destination with picnic grounds, a dance pavilion, a carousel, and a searchlight that illuminated the falls at night. The line ran into receivership in 1935 and the Great Falls service was abandoned. The trolley park land was leased out to various concessionaires over the next two decades. In January 1953 the Fairfax Park Authority bought the property using funds originally set aside to acquire right-of-way for the George Washington Memorial Parkway. The land became a county park, then in 1966 was transferred to the National Park Service as a unit of the Parkway system. The carousel from the trolley-park era kept operating until Hurricane Agnes destroyed it in 1972. The picnic grounds are still in use.

Great Falls Park covers eight hundred acres on the Virginia bank of the Potomac, accessed from Old Dominion Drive off Virginia Route 193, with a twenty-dollar entrance fee per vehicle. The park has fifteen miles of trails, three viewing overlooks on the cliffs above the falls, a visitor center, and the canal ruins. Rock climbers work the cliffs in Mather Gorge below the falls. The water above the falls is closed to swimming and wading; the water below has been a popular flatwater kayak run since the 1960s. Tom McEwan was the first kayaker to run the falls themselves, in 1975. The falls became a regular destination for expert whitewater paddlers in the early 1990s and remain rated Class 5-6 on the international scale, near the maximum of what whitewater kayakers will run. The Maryland side of the river is in C&O Canal National Historical Park, which has its own different views and approaches. The two parks together preserve nearly the entire cataract.