Between the ages of 9-11 my friend lived next to a disused 'Asylum' hospital. It was on big grounds and completely unlocked - all the patients rooms, theatre, kitchens & chapel etc still had lots of personal belongings (postcards/ letters/ china etc) (we used to read the letters and some were very sad) and it felt like a ghost town. Literally no-one ever was there. We used to collect daffodils from the grounds in spring and play in the buildings - then we discovered a series of underground passages that went underneath the hospital - no lights, five of us holding hands and scaring each other as we went underground and tried to find a new exit out - the amount of pipes and sharp things bumping into our heads and eyes - it would be considered a H&S nightmare today. It was great fun though. It's all been developed and turned into posh houses now, but I always wonder if the tunnels have been blocked up when I drive past :-) great memories
http://www.nottinghamhospitalshistory.co.uk/page148.html