(一):Have you been to the Purple Forbidden City?

您去过紫禁城吗？

A: Have you been to the Purple Forbidden City?
甲：您去过紫禁城吗？
B: Not yet.
乙：还没有。
Have you ever been to ...?

What else... have you ever been to Beijing?

(二):Just as the saying goes “The Great Wall is a must”.

俗话说“不到长城非好汉”。

A: Just as the saying goes “The Great Wall is a must”.
甲：俗话说“不到长城非好汉。
B: Yes, that's a famous saying.
乙：是啊，这句话很有名。
They say...

As they say...,

…，as the saying is.