This kinda thing interests me...
I heard mention of this place recently on the BBC and searched for some photos. It is an old mental hospital, build in the late 1840's and I used to live near it for a while many years ago. I never got close to it, and I regret that, the only views of it I had were from the gates. I read on it a bit; it was an impressive building, and apparentlyfor the most part, self sufficient. Apparently it was a "pauper lunatic assylum", which in itself is scary. Counties at that time were in charge of the assylums, and if a certain poor person was bothering the wealthier of the county, it was a relatively easy procedure to have them put into the assylum. For the most if you went into there you never came out. Ever. They had their own cemetry on the grounds. There are reports of a lot of cruelty in there, but that seems to standard procedure for places of that kind in that era. There was no emphasis on rehabilitation, just containment.
The crime of bearing a child outside of wedlock apparently could also land you in there.
An anomoly was the alleged "secret pathway", I have only heard of this from stories of people in the area, and have seen no written evidence. There is a nearby train station, New Southgate, and apparently the wealthier and noble, who had "lunatic" family members used this pathway to get the "patients" to the hospital without embarrassement. This contradicts the "pauper assylum" description, but who knows?
The place sports the largest corridor in Britian. Strangely (or maybe not), the entire complex is now a luxury housing complex, and the old church has been turned into a gym. I wonder do any of the former residents wander the halls at night?
I really regret not having got in there somehow with a camera and seen what it looked like before it had all been changed. Mind you that was pre-digital days, and anyway I didnt have any money then.