It is not just big houses and historic properties: there will also be schools (such as Stowe in Buckingham), follies, factories, farms, windmills, courtrooms and village churches. One of the most unusual sites is the Snailbeach Mine in Shropshire which dates from Roman times and boasts the finest set of preserved lead mine buildings in the UK.
Next weekend (September 20-21), London will hold its own version, called Open House. A full directory of properties is included in the September edition of Country Living magazine, or telephone 0891 800603 for Heritage Open Days, or 0891 600061 for London Open House (though watch out, calls cost 50p a minute).
The Beamish Open Air Museum has been voted European and British Museum of the Year. Set in the countryside of County Durham, it illustrates life in the north of England in the 19th and early 20th centuries by putting buildings of social and industrial significance into context. As a forerunner to National Construction Week (October 13-23), a hands-on construction weekend on October 7-8 will aim to introduce primary and secondary pupils to the tools and techniques of building. Details: Derek Rees, Construction Industry Board, 0171 636 2256.
The Empire and Commonwealth Museum in Bristol is about to embark on its most ambitious project - a Pounds 20 million transformation of Temple Meads Station in Bristol, designed by Isambard Kingdom Brunel. This is reputedly the oldest surviving major railway terminus in the world. The museum aims to restructure the passenger shed, the engine shed and the vaults beneath to provide a series of exhibition galleries, education rooms and public amenities. Already the project has unearthed seven tonnes of archive material. It is now seeking Lottery funds to complete the redevelopment.