In August 2007, the world's first public museum, the Ashmolean, set a challenge for young artists to create a vision for the 21st century. Korky Paul (pictured below), the artist and book illustrator, asked children aged between four and 16 to "picture the magnificent, marvellous and magical new Ashmolean in 2009". The award ceremony took place on January 27 and the winning artwork is in the café lobby until March 24. The first, second and third prize entries in three age ranges - four to seven, eight to 11 and 12 to 16 - are on display, together with a selection of the runners-up.

You are unlikely to miss the winning artwork from each age group because the lead sponsor of the competition, the Oxford Bus Company, is parading it on the mega-rears' of two park-and-ride buses throughout 2008.

Korky Paul and the museum director Christopher Brown presented the winners with laptop computers provided by HBG, the construction company responsible for the rebuild.

I asked the illustrator of Winnie the Witch how they made their choice. He said: "It took us a whole caffeine-powered day to do it. The team of judges made a personal selection of ten each from all the hundreds laid out, and we used those as the starting point of a difficult task.

"As part of The Big Draw, I ran workshops for 75 children and encouraged them to draw in their own style. I am keen to promote drawing which unleashes the imagination, so I am delighted to have taken part in judging this competition."

The winning entry in the 12-16 section, by Alice Eccles of Kirtlington, is of a standard of draftsmanship of which I am sure Korky Paul himself would be proud. It is hard to believe that Alice is only 15. Her sophisticated architectural drawing was no carbon copy. She told me she loved the structure of the crane and used it to provide drama and contrast. It is a very successful composition and so I was delighted that Alice is considering a career in art. She said: "I want to begin by studying art history and that is why I love coming to the Ashmolean."

Christopher Brown said the museum was proud to have the largest crane in Oxford. Many of the young artists had visited the building site and were equally impressed by it. It was central to the painting by Edward Saunders of St Barnabas School and winner of the eight to 11 age group. He perches figures precariously, looking at the looming crane. Wit also featured in Lucy Southam's winning entry in the four to seven section. She called it A load of visitors for the Ashmolean. A consignment of smiling people is being transported in a digger! The quality of entries from this young age group was outstanding. No wonder it was hard choosing.

Second in this age group was Stella Saunders, from Kennington. She picked up a leaflet on a visit to the museum and decided to have a go. Her version of the Ashmolean is in technicolour and elongated. She told me: "I love drawing people and dressing them in bright colours." Her visitors admiring the museum represent the real ones who come in all shapes, sizes and ages. You can see the work of the nine prize-winners reproduced on the side of the portable building in front of the museum until 2009.

The originals and some of the great runner-up entries are on display, along with photographs of school parties on the hard hat tours. One entry inspired by such a view had the apt title You don't have to dig deep to find a treasure at the Ashmolean. You have until March 24 to enjoy them.

Why not linger over a coffee in the super café afterwards? We must wait until 2009 to see the 39 new galleries arranged on a theme of Crossing Cultures/Crossing Time, but Christopher Brown says the work is proceeding on time and to budget.

We can still enjoy time travelling during the redevelopment. One picture depicts a family in tears beside the pyramids asking "Would it just be easier to go to the Ashmolean?" The Egyptian collection is a children's favourite and one of the greatest glories of the museum.

After viewing the children's art in the café lobby, do visit the second part of the exhibition of Chinese Prints (1950-2006) which closes on February 24. If you would like to have a go yourself, the acclaimed artist Qu Lei lei is running a calligraphy and brushwork workshop tomorrow. Tel: 01865 278015.

There are hour long Highlights of the Ashmolean' tours every Saturday from 11am. These are free as is entry to the museum but a donation to the education fund is appreciated.

Can't spare an hour? There are Ten minute treasure' talks every Friday at 12.15pm. If you are unable to see the show before it closes, go to www.ashmolean.org/competition to view the children's art.

You can view an artist's impression of the redesigned Ashmolean on the Internet (www.ashmolean.org). Go to Transforming the Ashmolean' and click on film'. Opening times: Tues-Saturday 10am-5pm, Sundays noon-5pm.