On a 144 hour Transit free Visa to Beijing is excursion to Ming tombs allowed

Hi, a while ago, I determined here that I qualify for the 144 hour transit free of visa for a trip to BJ for a cruise starting from Tianjin. My question is while in BJ for 3 days, before leaving on our cruise from Tianjin, are we allowed to do excursion to the Ming tombs and Great Wall of China?