What are National Parks?
25 April 2012 Last updated at 06:53 BST
National Parks were created in 1951 but we have a group of illegal protesters to thank for them.
Celebrations are now taking place to mark the 80th anniversary of the 'mass trespass' on a mountain which led to a change in the law.
Walkers from all over Britain are recreating the moment in 1932 when protesters dared to walk over Kinder Scout, a mountain in the Peak District.
The 400 protesters were angry that rich landowners could stop other people walking in the open countryside.
Their campaign led to a law change, as Ricky explains in his report.