Geograph - photograph every grid square

Dilston Castle is a fortified solar Link tower, built by Sir William Claxton, c1417. It was enlarged in Elizabethan times and a Jacobean manor house, Dilston Hall, added in 1622. They were both incorporated in a palatial mansion belonging to James Radcliffe, 3rd Earl of Derwentwater. This was surrounded by ornate gardens, all in a grand style. After his execution for high treason in 1715, and the death of his son in 1731, the Derwentwater estates were seized by the Government and passed to the Greenwich Hospital Trustees. The Hall, now in a ruinous state, was demolished in 1765, leaving only the original tower house. Many stories about the estate, hall and the Radcliffes passed into local folk lore.
Now, all that remains of Dilston Hall are alterations made to the Castle, the Chapel, the Gateway and Lord's Bridge over the Devil's Water, along with recently excavated remains of the buildings. The current Dilston Hall (a large country house and former maternity home) and 9 acres of park, woodland and gardens, which include the ruined castle and chapel, are operated as a training college by the mental health charity, Mencap.
Archive Link
According to Dan Brown's novel, 'The Da Vinci Code', James Radcliffe's brother, Charles, was the 20th Grand Master of the Priory of Sion from 1727. This was said to be a shadowy organisation guarding secret knowledge of the whereabouts of the Holy Grail. Perhaps, with the archaeological excavations continuing annually around the castle, it'll actually be found there.