Blaise Castle is a folly built in 1766 near Henbury in Bristol, England. The castle sits within the Blaise Castle Estate, which also includes Blaise Castle House, a Grade II* listed 18th-century mansion house. The folly castle is also Grade II* listed and ancillary buildings including the orangery and dairy also have listings. Along with Blaise Hamlet, a group of nine small cottages around a green built in 1811 for retired employees, and various subsidiary buildings, the parkland is listed Grade II* on the Register of Historic Parks and Gardens of special historic interest in England.

The site has signs of occupation during the Neolithic, Bronze Age, Iron Age and Roman periods. After the Dissolution of the Monasteries the site was sold. In 1766 Thomas Farr commissioned Robert Mylne to build the sham castle in Gothic Revival style. After Farr’s bankruptcy, the estate was sold several times until purchased by John Scandrett Harford, who demolished the previous dwelling in 1789 and built the Neoclassical Blaise Castle House. His son, also named John Scandrett Harford, continued with the development of the buildings and estate, which his family occupied until 1926, when it was bought by Bristol City Council. The park was laid out by Humphry Repton in the early 19th century. The estate is now owned by Bristol City Council. The house is run as a museum by the Bristol City Museum and Art Gallery and holds a variety of collections. The Picture Room, added in the 1830s, is hung with paintings, mostly of the 19th century. There are selections on display from Bristol Museum’s 10,000 items of historic costume, and of toys from the 18th century to the 1980s.

Flint fragments show Blaise Castle Estate was probably first inhabited by Neolithic farmers. There is more definitive evidence for Bronze Age, Iron Age and Roman activity through the distinctive hill-forts in the area and other archaeological finds. The value of this historic landscape was recognised when it became a scheduled monument in 1982.

The land was granted to the Bishop of Worcester as part of the Kingdom of Mercia before the Norman conquest. During this time, when it was the property of the church, the estate had a chapel dedicated to Saint Blaise, which has given the estate its name.Following the Dissolution of the Monasteries, the estate was granted to Ralph Sadler who let it to tenants until 1675. A large part of the estate was bought by Sir Samuel Astry of Henbury.

The chapel’s last ruins were removed in 1707.

On a hill above the gorge is a sham castle in Gothic Revival style overlooking Bristol, Avonmouth and the Avon Gorge, with views across to South Wales on a clear day. It was built in 1766, by Robert Mylne, on the site of a chapel dedicated to Saint Blaise. The folly is reputed to have cost £3,000.The circular building is built of local ashlar stone with limestone dressings. It has three turrets with crenellated parapets.

Denham Skeate opened the site to the public.

It was open to paying visitors and a popular attraction from the first with excellent views on a clear day. Vessels could be seen pᴀssing on the River Avon from the castle, and the hills and mountains of Wales were visible beyond the river. The castle was mentioned by Jane Austen in her novel Northanger Abbey. John Thorpe, planning a trip to Bristol with Catherine Morland and her brother, describes the castle as “the finest place in England – worth going fifty miles at any time to see.

It was inhabited into the 20th century and was elaborately decorated internally. It is a Grade II* listed building and was restored in 1957.