Dox Castle

Dox Castle is a 4,780 ft summit located in the Grand Canyon, in Coconino County of northern Arizona, US. It is situated four miles north-northeast of Havasupai Point, two miles northwest of Evans Butte, and 2.5 miles southwest of Holy Grail Temple, where it towers 2,500 ft above the Colorado River.

Dox Castle was named by William Wallace Bass and George Wharton James for Virginia Dox (1851–1941), who was the first white woman to visit this part of the Grand Canyon in 1891. Holy Grail Temple was originally named Bass Tomb by Virginia Dox, for William Bass, Dox's guide into the canyon. Impressed by her, Bass named Dox Castle shortly after she left. This butte's name was officially adopted in 1908 by the U.S. Board on Geographic Names. According to the Köppen climate classification system, Dox Castle is located in a cold semi-arid climate zone, with precipitation runoff draining west to the Colorado River via Shinumo Creek.

Dox Castle is composed of Cambrian rock from the Tonto Group, overlaying the Proterozoic Unkar Group at river level. Levi F. Noble named the Dox Formation because of exposures in a tributary to Shinumo Creek below Dox Castle.