The 11,000 square foot structure, the largest ever featured on the Channel 4 programme, involved demolishing a 17th-century folly, drawing comparisons to a "prison" or "car park" from residents.
The couple behind the build, Piers and Emma, saw their budget spiral from an initial £2m to £5m, with an estimated further £1m needed to finish the project.
The unfinished "21st-century castle" is now listed for sale with Sotheby’s Realty for £7.95m, with the listing saying “final completion expected in 2025”.
Local villagers expressed strong, often negative, opinions about the "vanity project," though some found the ambitious build impressive.