The most impressive features of Helmsley castle are its large earthworks with two deep ditches that are cut down through the outcrop of rock on which the castle stands. This ringwork formed part of the original earth and timber castle built in the early 12th century by Walter Espec. Following his death in 1154 the castle passed to his brother-in-law, Peter de Roos, and it would be held by descendants of the de Roos line until 1688.