It is forbidden for a Jew who is impure to enter certain parts of the Temple Mount; many authorities prohibit entering it nowadays at all.
What about a non-Jew? Is someone who isn't Jewish permitted to ascend the Temple Mount nowadays?
Jews who are impure from a corpse and non-Jews can enter the same parts of the Temple Mount. (Rambam Biat Mikdash 3:5)
In the Temple times a non-Jew would be killed for entering prohibited parts of the complex. At least, that's what the sign there said.