Castle was built by Howell Coetmore, who fought under the Black Prince as commander of longbowmen at the battle of Poitiers in 1356. Following the Wars of the Roses the castle was rebuilt in around 1490 by Meredith, founder of the Wynn dynasty and a leading supporter of King Henry VII. Originally a fortified house, Gwydir acquired additions in the 1540's (incorporating reused gothic building material from nearby Maenan Abbey), and was given a fine Elizabethan porch and gardens in the 1590's. Further additions were made in 1828 to designs by Sir Charles Barry, architect of the Houses of Parliament.