China visa for a 1 day tour to the Beijing city centre / Great Wall.?

I am a Maltese citizen currently living and working in Luxembourg and am travelling from Frankfurt to Sydney and back. During my 5 hours (going) and 8 hours (coming) stopover in Beijing Capital Airport, I would like to take a short tour to the city centre / Great Wall.

Is it possible to get out of the airport during transit and if yes, do I still need a VISA for a few hours visit?

Thank you