Arthur's Rock is a prominent 6,780-foot pegmatite formation in Lory State Park near Fort Collins, visible from much of the city and from Colorado State University. Named for former landowner Arthur Howard, it became one of the park’s best-known landmarks after the park was established, with one of its most popular hiking and biking routes leading to the summit. Geologically, the rock formed 1.7 billion years ago as part of the Log Cabin Batholith and was later exposed as softer overlying sedimentary layers eroded away. Its surroundings mark a transition from Great Plains shortgrass prairie to Front Range foothills vegetation.