The Lunatic Asylum, as such hospitals were known at the time, was located on Friern Barnet Road at . It is shown on of 1876-1881 which marks Colney Hatch Park in the area centered on Springfield Road in New Southgate, in the London Borough of Enfield. The asylum itself was further west in what is now generally called Friern Barnet, in the London Borough of Barnet.
It was in close proximity to the Great Northern Railway and had its own station.
Originally plans were made and land purchased for this asylum to built close to the existing 1st Middlesex County Asylum at Hanwell on ground that lies just on the other side of the Grand Union Canal. Perhaps the number of other asylums already in the area led to the decision to have it built elsewhere. The architect was Samuel Daukes, the design of which was based on the advice of John Conolly, the superintendent of the 1st Middlesex Asylum (Hanwell Asylum) in Southall. It opened on the 17th of July 1851 and was officially referred to as the 2nd Middlesex County Asylum with William Charles Hood (1824-1870) being its first medical superintendent.
In 1889 its control was transferred to the London County Council. It became known as the Colney Hatch Mental Hospital in 1918 until it was renamed Friern Mental Hospital in 1937, the name later changing simply to Friern Hospital in 1959. After a long period of decline the hospital closed in 1993 and the building was converted into luxury flats under the name Princess Park Manor. While much of the hospital's grounds were also sold off for building, much also remains in public hands and is accessible to anyone.