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 nin…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.