Severalls Hospital (Second Essex County Asylum), Colchester
Severalls Hospital has been on my list ever since I started exploring really. It took a while but I finally got here, and after about half an hour trying to figure out how to gain access, we managed it. And worth it it certainly was. What a massive place! I could spend days in here. Literally.
As of April 2012, I am currently planning another visit here, partly to do the water tower, and also to finish the wards we started and didn't finish. Watch this space for more Severalls!
Wikipedia Article for Severalls
My Severalls report on 28 Days Later UE Forum