Originally a mansion house in Woodhead, it became locally known as a “Castle” and was built by John Lennox in the 16th Century. In the 1830s John Kincaid Lennox commissioned Glasgow architect David Hamilton to build a new house to the north of the pre-existing house, on higher ground, and plans were to demolish the original Woodhead house.
Mrs Kincaid Lennox asked for it to only be partially demolished so the original could be purposefully left as a ruin, with ivy and climbing shrubbery planted to add character to the remains of the building. The new house took four years to build and was built in the Scots baronial style. The Lennox family sold the property in 1927.
Lennox Castle has had various uses over the years including a temporary hospital during the First World War and in 1936 it opened as, what was then called, a “Mental Deficiency” hospital, with also a separate Maternity hospital in the grounds until the 1960s.

References
Old Lennoxtown, Campsie Glen, Milton of Campsie and Torrance – John Hood
Walks around Lennoxtown – Strathkelvin District Council