The Great Wall of China ..... maybe.

… because you can hardly see it from an airplane. 

I flew out of Beijing on Wednesday morning and it was amazingly clear and sunny over the mountains, with crisp morning shadows.  I maintain that I could just see the Great Wall of China snaking across the mountains, but this hasn’t been verified by an actual local person.

Mountains and plains stretching towards the Gobi Desert

About quarter of the way across China it got cloudy, but also a bit curvier…

Swirly mountains, quarter of the way across China

And then as we got nearer to Chengdu (half way across China), it got more and more cloudy, but also green – at last. 
I was told that if it was clear blue sky in Chengdu, the local engineers I was due to meet would take the day off and sit by the river.  But they have only had pure blue sky twice in the last two years.  It is a city of mist.  Local wisdom has it that the women in Chengdu are the most beautiful in all of China because it is always overcast so they are pale and their skin never ages.  Hopefully it will have some effect on me. 

Sichuan province