A 900-year-old Viking sword is coming home to Yorkshire after being kept behind closed doors for more than 50 years.

The Cawood Sword, found in the River Ouse at Cawood, near York, is only the fifth sword of its type to be found and by far the best preserved.

It remains nearly fully intact with little rust and has many of its original features clearly visible, including a mysterious inscription that has never been solved.

After 50 years in private hands the sword has now been acquired by the Yorkshire Museum, in York, where it will go on show for the first time in its home county this week.

Andrew Morrison, curator of archaeology at the museum, said: "This is an outstanding sword, one of the best preserved Viking swords ever found. It's in amazing condition and it is hard to believe it is nearly 1,000 years old.

"The combination of its age, condition and the mysterious inscription make it a really important acquisition for the museum, especially as it was originally found close by.

"We are thrilled that it is coming back to Yorkshire where it belongs."

The sword was found in the late 19th century in the river, but the exact date and circumstances of its find remain a mystery.

Andrew said: "We are really keen to get the people of Cawood involved in finding out more about this sword.

"The Cawood Castle Garth Group has already been extremely helpful and we look forward to working with them to try and find out as much as we can about it."

Because the sword has been in the hands of private collectors for more than 50 years, Andrew is also keen to apply modern science, such as X-rays, to it to see that will reveal anything new.

The sword will be on display for two weeks from tomorrow until January 7 before it is removed for conservation and research reasons.

However, it will be going back on show in time for the Jorvik Viking Festival in February 2008.

The Cawood Sword can be dated to 1100. It is unclear how the sword ended up in the River Ouse, but it was found close to Cawood Castle which was the summer palace for the Archbishop of York who may have also owned the sword at some point.

The site was, at an earlier time, a Viking Lord's manor house.