一个你不知道的地方 英语怎么说？

an unfamiliar place
be a stranger to s.p
somewhere you don't know

A place where you do not know 或
Somewhere you do not know

a place that you have ever never know.

a place you don't know

A place that you don't know 也可以省略that

that 引导的定语从句可以省略that

One place you have no idea. 口语一点吧~