What's the best translation to 「要看两千年的中国，去西安；要看一千年的中国，去北京；要看一百年的中国，去上海；要看十年的中国，去深圳」？
要看两千年的中国，去西安；
Wanna taste the flavour of China 2000 years ago? Go to Xi An!
要看一千年的中国，去北京；
Wanna taste the flavour of China 1000 years ago? Go to Beijing!
要看一百年的中国，去上海；
Wanna taste the flavour of China 100 years ago? Go to Shanghai!
要看十年的中国，去深圳
Wanna taste the flavour of China 10 years ago? Go to Shen Zhen!

The Chinese is not native, I would say. Is it a back translation from some English language tourist stuff?

Shanghai is rockin' and rollin', has not stopped at 100 years ago!