Charleville Estate is located on the edge of the town. One of Ireland's most splendid Gothic buildings, Charleville Castle, stands in this parkland setting which contains the King Oak, one of the biggest and oldest oak trees in the country. The castle is said to be haunted and was featured on series 1 of Living TV's "Most Haunted". The oak woodland is botanically an important survivor of primeval stock. The park was the location of the annual Tullamore Agricultural Show. However following the cancellation of the show for two consecutive years due to heavy rainfall the event was moved to a new location with improved drainage in the Blue Ball area, south of the town.