Q. Is it permitted for a Jew to enter the Temple mount in Jerusalem?
A. The Temple mount is the hill on which the sanctuary stood. The Kotel is the surrounding wall on the western side. It extends far beyond the open area where the crowds come to pray every day. The Temple was located within the compound on the hill but not so much in the centre as on the north-western side.
The mount retained its sanctity even after the destruction of the Temple because it was not the stones but the Divine Presence that made it holy.
Hence, just as in Temple times, anyone who is ritually defiled may not enter the area. But since we have detailed records of the measurements of the Temple, entry to part of the surrounds could be possible provided a person has ritually immersed and so long as they have taken off their shoes (Mishnah B’rachot 9:5).
The chief rabbi of Tel Aviv, Rabbi Chayyim David Halevi, stated in 1976 that there is definitely a permitted area which a Jew can enter subject to the above provisos.
There are obviously additional political considerations, but they are outside the scope of this answer.