An afternoon at a children's museum can be salvation for anyone travelling with young people; a corner of a foreign country where there are other children to play with, where noise and mess can be made - a reward for hours spent patiently accompanying parents on a city-break circuit of proper museums (yawn) and sights (unspeakable).

In general, children's museums are a city thing - Britain's main one is Eureka! in Halifax, West Yorkshire, which opened in 1992. The nearest London gets to one is Launch Pad at the Science Museum - a bustling area of scientific interactivity (the grain store and turntable are particularly popular) that will move, and grow in size, to the Wellcome wing when it opens next month.

At Eureka!, there are hundreds of children racing around, pretending to be mechanics in a garage of scaled-down cars or playing in a scaled-down television studio. There is a child-size branch of Marks & Spencer, a mini-post office and a little factory - a mini-town square, in fact, with recognisable high street names. Upstairs, children can see what really happens when they flush a loo, thanks to a see-through toilet, and play in a child-sized kitchen. Nearby is a giant mouth to explore, complete with a wobbly tooth. There are buttons to push and cogs to be turned, but signs are kept to a minimum. 'We're not feeding facts, we don't want to inhibit kids, we want them to feel that this is a fun, playful place,' says Eureka!'s new director Leigh-Anne Stradeski. Unlike more conventional museums, children's museums don't have a remit that includes preserving the past. There is nothing that can't be replaced or repaired.

So might Eureka! actually be a theme park, albeit one with a built-in Early Learning Centre-ish feel-good factor to assuage parental guilt? Stradeski rebuts the sugges tion: 'Exhibits here are much more sensory, tactile, textured and open-ended than theme parks can offer. Any activity that we design has education at its heart.'

Nor does she see a day at Eureka! as a soft option for families: 'We don't want an adult reading at the side or just watching their child play,' - although, below us, at that very moment, a father was doing his best to read the paper while his daughter played by the roadworks in Eureka!'s town square.

Before Eureka! opened, they asked groups of children what they would expect to find in a town centre. Most considered roadworks to be a vital part of modern urban living, although Eureka!'s designers incorporated a mini-archaeological dig into it as well to be true to the educational message.

Children's museums originated in the US. Today, there are more than 250 of them, and every US city has one. New York and Los Angeles have two.

The tradition in the US is still to design children's museums that encompass both arts and sciences, and typically have sections that recreate life in the past, although what constitutes the past is usually unnervingly familiar to anyone aged over 50. European museums, such as newMetropolis in Amsterdam or Experimentarium in Copenhagen, are more likely to concentrate on sci ence and the future. Actually, Eureka! feels like a more focused Dome, which isn't surprising as several of the Dome's designers cut their interactive teeth on Eureka! (and if the Body Zone's eyeball is at a loose end next year Eureka! wouldn't mind inheriting it - the staff think it is rather better than the one in their Me and My Body section.)

Equally, there's the same sort of commercial involvement as at the Dome. It's just as good to talk at Eureka!, as BT has sponsored the Communication Zone there too, although the message is subtler at Eureka!, since its main exhibit is a yacht, giving opportunities to practise semaphore.

True to its educational core message, the early days of Eureka! featured a café full of healthy eating options. The food is more playful now, with more in the way of burgers and chips. The early visitors had felt that junk food was more in keeping with a day out, but the bins with prominent information about recycling are still there.