http://www.heritageopendays.org.uk/about
Loads of places in Devon to visit
if you are thinking of visiting any of these it might be an idea to phone them before you set off as not all places may be offering free access for the full four days. For example, A La Ronde, http://www.nationaltrust.org.uk/a-la-ronde/ t'other side of the estuary, is offering free access on Saturday 13th and Sunday 14th only.