Helmsley Castle began life as a wooden fortification, built in 1120AD by Walter L'Espec. It was surrounded by a 30ft deep double ditch cut from the solid rock outcrop on which the castle stands. Unusually, it featured no central motte - the earthen mound upon which early Norman fortifications were usually constructed.

In 1186AD, Robert de Roos began the task of improving the original structure and transforming it into a stone fortress. The timber palisades surrounding the castle were replaced by a stone curtain wall, complete with defensive towers. The east tower (which also served as the keep), north and south gates and parts of the west tower all date from this period.

Little changed during the 12th Century, but through the 13th and 14th Centuries, various nobles continued to expand and remodel various parts of the castle - including the addition of a further two stories to the east tower. The most striking addition to the castle didn't occur until the 16th Century, however, when the old hall was converted into a Tudor mansion.

The castle's defences weren't tested until the 17th Century, when in 1644AD, the English civil war arrived at Helmsley. Sir Thomas Fairfax laid siege to the castle, with the defenders holding out for three months before finally surrendering to parliamentarian forces. Subsequently, the east tower, curtain walls, gates and towers were all "slighted", putting the fortress beyond use. The east tower suffered the heaviest damage, being virtually destroyed by explosives. The Tudor mansion was spared, however, and continued to be used as a place of residence until the early 18th Century.

The ruins of Helmsley Castle remain impressive. Although mostly destroyed, the east tower still dominates the site, rising high above the surrounding buildings. The Tudor mansion is still extant, and a walk around the defensive ditches offers a dramatic impression of the defences that any would-be invader would once have faced.