We spent four foggy, smoggy days in Beijing late January and were able to take a day trip to Mutianyu. What a great way to get out of the city and above the low lying fog. In January, there are few tourists and you essentially have the wall to yourself. I cant imagine the feeling one would have in the summer jostling with tour bus groups, but in January one can find peace and quiet and are able to enjoy the wall for what it once was, a fortress. Great views and relatively easy walking on this section. I recommend taking the chairlift up and tobogganing back down. We had spoken to others that had visited the wall at locations closer to Beijing and all recommended taking the extra time to go to Mutianyu. Loved it !!