Never been myself but Glastonbury to upstate New York is a bit of a trek lol. That said I've read quite a bit about Millbrook and the history there is genuinely grim, which tends to be the common thread with these old sanitariums - the trauma just seems to soak into the walls somehow.
From what I've gathered the west corridor is where most of the activity gets reported, something to do with the old hydrotherapy ward. Would love to hear from anyone who's actually done an overnight there. Did you pick up anything on equipment or was it more of a personal, felt-it-in-your-gut kind of experience? Those tend to be the more compelling accounts in my opinion.
If anyone's got photos or EVP recordings please do share them here, we get a lot of "I felt something weird" posts and they're fine but the documented stuff is what really gets me going.