The monument includes an octagonal shaped building in the middle of the wide High Street in Dunster, known as `The Yarn Market' or market cross. The building is 9.4m in diameter and has a massive central octagonal based stone pier from which spreads a heavy timber framework with verticals, resting on a low rubble stone wall. A wide counter forms a sill to the openings on each of the eight sides, some being stone, others oak. The floor is cobbled. The timber framework carries a slate roof with a central wooden lantern surmounted by a weather vane with the initials `GL' and the date 1647. There are eight gabled dormers, each with three-light leaded wood casement windows with moulded wood mullions. It has wide prehanging eaves on bracket and pillar supports. The Yarn Market was built in 1609 by George Luttrell, who then owned the castle, and the date 1647 refers to repairs done by Francis Luttrell. Dunster cloth and kerseymere were sold there. The monument is Listed Grade I and in the care of the Secretary of State.