Since so many people are asking, on and off list, about Har HaBayit (The Temple Mount), i will break my own rule and describe the issues briefly. Yes, according to all views (except RAAVAD) the prohibition of entering the site where the Temple stood, while in a state of impurity, is exactly the same whether the Temple is standing or not. Since we are all in a state of impurity because of contact with the dead, and we lack the Red Heifer, entrance into the area of the Temple or its courtyard is strictly forbidden, EXCEPT if actually offering sacrifice, which may be done in impurity if most of the people are impure. The only thing lacking for offering the Passover Sacrifice, for instance, is governemnt and police permission.  For this, and many other sacrifices, the Temple itself is not essential, only the Temple site. For the rest of the Temple Mount, there is NO prohibition to enter, providing that one has immersed in a mikveh. The Temple Mount area is 500 x 500 cubits (750 square feet). Area was added by Herod on the South side, which is not actually sanctified. Where the Al Akhsa Mosque is situated, is clearly in the area added by Herod, and not part of the Temple Mount. So, at least theoretically, anyone can go on the Temple Mount, excluding the actual Temple area, after having immersed. BUT, we are not certain exactly where the Temple stood. There are three main theories. Nevertheless, most agree that the Dome of the Rock is on the site of the Holy of Holies. Those who go up rely on that view. If rabbis and archaeologists were allowed to have free access, that could be settled in an hour. Now, many rabbis hesitate to allow going up at all, until the Temple site can be clarified. Many more are opposed because you and I may be careful to immerse, and avoid the actual Temple area, but, once people are allowed up, who will enforce their movements and actions? Some 40 years ago, a Temple Mount activist put on an army uniform, and went to see Rabbi Elyashiv, the doyen of the Lithuanian Yeshiva community. The man pretended to be crying inconsolably. He told Rabbi Elyashiv that he was being assigned by the army to guard the Temple Mount, and he knows that it is a grave sin. Rav Elyashiv is reported to have said "There is hardly a law more clear than the permissibility of going on to the Temple Mount after immersion. We only say that it is forbidden in order to keep people from going there indiscriminately". Rabbi Mordechai Eliyahu, the late Sepharadic Chief Rabbi, advocated building a synagogue on the Temple Mount in a part definitely not within the Temple area, with an entrance from outside the Mount, with no exit to the other parts of the Mount. Beyond this is ideology and politics. A concept of early Zionism was "conquer the Land with your feet". if Jews go to an area, it will become ours, if they stay away, it has already been ceded. Others argue that any attempt by Jews to have a presence on the Mount will lead to violence and bloodshed. This goes back to a dispute between the Babylonian and Jerusalem Talmuds. The Babylonian envisions a supernatural deliverance. G-d will take all the evil off the Mount, and Messiah will rebuild the Temple. (According to RASHI, the Temple will descend fully built from Heaven). The Jerusalem Talmud sees it as our constant obligation to rebuild the Temple whenever that would be feasible, completely independent of Mashiach. Therefore, there are those who wish to go to war for the Temple's rebuilding, and those who want to keep peace at any cost, with letting G-d take care of the rebuilding when it will please Him. I hope this helps in understanding the background of the dispute.