Lay over tour to the Great Wall of China

Hello,
We arrive early morning from Switzerland on our way to Thailand with a 14 hour stop in Beijing. We would like to go on a guided tour to The Great Wall of China and also the forbidden city, if possible. Will this require a visa or will it be enough with the 72 hours permit? We are Danish passport holders and I do seem to understand that we are covered by the agreement, but I am a bit uncertain whether we can go to these places or only the city centre. Thanks a lot!