On a hot summer’s day, getting children into a museum can be a sticky proposition. They want to run around outside and eat their body weight in junk food, and compulsory visits to overcrowded, overheated rooms can be a short-cut to frayed tempers and rows.

But the Weald and Downland Open Air Museum in Singleton, West Sussex, offers a happy compromise in the battle between ketchup and culture. Because, as it says on the label, this museum is outdoors, set in 50 acres of lush South Downs countryside.

It holds a collection of historic buildings from the south-east of England, dismantled from their original locations, reassembled in the museum grounds and opened up to the public. A precondition of these buildings being brought here is that they were at risk of destruction where they once stood - so the museum operates as a kind of sanctuary for old buildings threatened by the bulldozer.

As an example, the building where you buy your entrance ticket once stood on the site now occupied by the Channel Tunnel terminal near Folkestone. Instead of being flattened, this 16th-century farm building was taken down brick by brick and put back together at the museum.

The buildings range from the medieval to the Victorian and are all examples of the everyday homes and work buildings that would once have been common across the southern counties. These aren’t the stately homes and big houses you usually see on the historic buildings tourist circuit, these are the real homes of ordinary people - and in many ways they tell you much more about the era than the show homes of the aristocracy.

I was particularly taken by Poplar Cottage, originally from Washington, near Steyning. This two-up, two-down cottage had been built in the mid-16th century as the home for a family of landless labourers. It was beautifully crafted from stone, wood and plaster, and had its own kitchen garden. And the smell of wood smoke had me sitting by the fire, ready to fall asleep. I couldn’t help but wonder what the Elizabethan poor who originally lived here would have made of the prices being paid today to live in cramped concrete apartments.

The houses also show how buildings in the English countryside could be used and adapted continuously for centuries. A house brought from Walderton in Sussex appeared externally to be 17th century, but once dismantled it was found to be medieval, and had been modernised into the style of the 1600s. This reworked building was then divided up into smaller units in the 1830s, and was finally rescued from demolition in 1979.

These are all “real” buildings, and one of the excitements of this walk-through history is that you can imagine how many dramas of people’s lives have been played out here. How many people were born and died in these bedrooms? How many raucously good nights were had in these halls? How many stories were told by these fires? When you walk up a medieval staircase, you have to wonder about all the generations lying in bed who heard the same creak in the stairs.

All these houses have plenty of character. Made without power tools and from materials locally available, they have a slightly off-centre, organic look. It’s not all straight lines and sharp corners; instead there’s a home-made feel that makes them sit naturally in the landscape.

The museum shows how the materials used were crafted, with displays on brick-making, a blacksmith’s workshop, and information about carpentry. They were constructed using large wooden beams cut by hand using the type of saw-pit on show in the museum. This was a trench used by woodworkers to cut up trees, using huge, two-handed saws.

This pre-steam, pre-electric world depended on physical muscle, and in the beautiful 600-year-old Bayleaf farmstead a display shows how medieval labourers consumed twice the daily amount of calories that we would today because of the sheer hard work expected of them.

The museum also includes a water mill, toll cottage, Victorian country schoolhouse, charcoal burner’s camp, joiner’s shop, wagon shed and a treadwheel, used to draw water from a deep well. All you need is a couple of men with sideburns and a suicidal woman and you’ve got the best part of a Thomas Hardy novel.

When you look at these charming old houses, it’s shocking to think they once faced demolition. There’s an engaging medieval shop from Horsham, and if you look at the photo of the drab 1960s building that replaced it, you wonder what’s meant by progress.

What also makes this museum so much of a hidden treasure is its unassuming, low-key approach. It’s run by volunteers and there’s little of the commercial shakedown you expect in tourist attractions. And because it’s spread out over so much ground, there’s a relaxed, unhurried feel to the place - you feel you’re taking a walk in the countryside as much as visiting a museum.

And, even better, it will exhaust the children into silence.

Weald and Downland Open Air Museum, Singleton, Chichester, West Sussex PO18 0EU. Adults pound;7, children pound;4. Tel: 01243 811348