from the website:
"Heritage Open Days celebrates Englands architecture and culture by allowing visitors free access to interesting properties that are either not usually open, or would normally charge an entrance fee. Heritage Open Days also includes tours, events and activities that focus on local architecture and culture.
Free of charge and literally on peoples doorstep, Heritage Open Days is an event for everyone."
You can search for events near your County here: http://www.heritageopendays.org.uk/directory/
Sorry if this has been posted before - did a search for it but couldn't find previous post on this.