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This summer the has opened its doors to some of the nation's best-loved cartoon characters and allowed 's mischief-makers to run riot across the country.

Dennis the Menace and Gnasher kick off the summertime chaos as they conquer medieval Powis Castle in Welshpool.

The Beano front page: Dennis and Gnasher at Powis Castle

Dennis and Gnasher at Powis Castle

Dennis and the hedge menaces

This is the first ever time that the National Trust has given fictional characters keys to all of its 300 homes and access to the 617,500 acres of land it cares for.

The Beano characters have invaded historic properties to help the trust bring its places to life and prove that its doors are open to all.

Other Beano characters have had some cracking fun at National Trust properties including The Numskulls, who live inside Edd's nostrils (of course). They are sneezed out at Edwardian Surrey estate Polesden Lacey into a game of croquet - and a planned bug hunt - to enjoy the buzz of bumblebee racing. Minnie The Minx takes her dad on a manic trip to Northern Ireland to discover the iconic Giant's Causeway and find the giant Finn McCool himself, and Billy Whizz has a fast-paced day, topped off by a good night's sleep in Lyme Park's Edwardian Nursery.

John-Paul Murphy, head of brand marketing at the Beano's publishers DC Thomson, speaking about Dennis' visit to Powis, said:

"We couldn't think of a better way to prove what fun kids can have at 'Gnashional Trust' properties than by letting the world's most famous menace and his friends from Beanotown loose on them. Dennis hasn't let his own 60th anniversary affect his ability to cause his own brand of havoc and it is a fitting birthday treat for him to become 'King of the Castle' at Powis. We're sure Beano readers will have just as much fun as the characters when they visit the venues featured in our comic this summer."

Tony Berry, visitor experience director of the National Trust, added:

"We are delighted to open our doors to The Beano and all of its mischievous characters. The National Trust and The Beano are both British institutions and we are hoping the news that we have opened our doors to them all will encourage families to take a leaf out of Dennis' book and organise a trip to one of our places. As our black and red stripy friend says: 'a menace always has a plan' and this summer should be no exception."

If you're looking for things to do with your little menaces over the school holidays take a look at the website.

The Gnashional Trust issue of The Beano goes on sale Wednesday 27 July 2011. For a behind-the-scenes look at the takeover visit .