May one visit the Temple Mount?
The Temple area contains Kedusha even today in its state of destruction. Accordingly, just as in Temple times there existed restricted areas of entry, so too in today’s times, there are certain areas in which it is forbidden for a Jew to enter. Some of these areas are prohibited under the penalty of Kareis as explained next.
The areas of restriction: The Temple Mount contains a number of areas with Halachic restrictions of access. For example, the Halachically defined area of the Temple Mount in general [called the Har Habayis] is permitted in entrance for only one who is pure from the impurity of a Nida, Zav/Zava [Baal Keri] and Yoledes. The area however remains permitted for entrance to a Tmei Meis. A Nida, Zav/Zava, [Baal Keri] or Yoledes who enters into the Har Habayis, is liable for lashes. The area of the Cheil and Ezras Nashim is only permitted in access for one who is pure of Tmei Meis. A Tmei Meis who enters into the area of the Mikdash that is completely holy, such as the Ezras Yisrael and inwards, is liable for Kareis. The area of the Kodesh may only be entered by Kohanim during the time of Avoda. A Kohen who enters into the Kodesh not during times of Avoda, is liable for lashes. The area of the Kodesh Hakedoshim may only be entered by the Kohen Gadol, and only on Yom Kippur. One who is not a kohen Gadol, or even a Kohen Gadol who enters not on Yom Kippur, is liable for death in the hands of Heaven.
The location of the above areas: It is difficult to measure the location of the above areas of restriction due to several reasons. First off, the original Har Habayis was 500 Ama by 500 Ama, while the current Har Habayis area is much larger than this. Accordingly, there exists areas by today’s Temple Mount that do not contain the Kedusha of Har Habayis at all, and permitted in entry by every Jew. The problem is however that it is most difficult to ascertain the precise areas that are not included in the Halachic Har Habayis. Where do we measure the 500 x 500 Ama from, and what is the exact measurement of an Ama in this regard? Both of these matters are under dispute. The Poskim dispute over where the location of the Kodesh Hakedoshim is, and therefore dispute as to where the practical areas of restriction are located. The Poskim also dispute as to the exact measurement of an Ama. Accordingly, what may be a restricted area to one opinion, is not a restricted area to another opinion, and what is an unrestricted area according to one opinion may be a restricted area for another opinion. Nonetheless, the mainstream approach amongst Poskim is that the center of the Kodesh Hakedoshim is by the rock found under the “Dome of the Rock” and from there one measures all the Amos of the Kodesh Hakedoshim, Kodesh/Heichal [100 x 100 Amos], Azara [From North to South is 135 Amos and from East to West is 187 Amos], Ezras Nashim [135 x 135 Amos], Cheil [10 Amos from the walls of the Beis Hamikdash, from East to West is 342 Amos, from North to South is 155 Amos, and is a total of 11 Amos from the Dome of the Rock], and Har Habayis [500 x 500 Amos]. While we know the exact measurements of Amos for each area, it is unclear as to how many centimeters each Ama contains [as stated above] and it is also unclear from where on the rock the measurements should begin.
The practical ruling of Gedolei Yisrael: It is evident from the Poskim, that in previous generations Jews customarily would visit the Temple Mount in order to see the Makom Hamikdash. Some Poskim of earlier generations defended this practice, going as far as saying that even entering a questionable area at times may be permitted, due to their great passion to see the Holy of Holies. Nonetheless, in both the previous and current generation, the Poskim and Gedolei Yisrael from all spectrums of Jewry, have severely warned the public not to enter the Temple Mount, including even the permitted unrestricted areas, lest he enter a restricted area and be liable for the severe penalty of Kareis. Meaning, that even if we can determine without shadow of a doubt the exact areas of restriction, or of questionable restriction, and the areas that are permitted in entry according to all, nevertheless, one should not enter even these areas, as doing so would cause others who are unaware or not G-d fearing to enter the prohibited areas.
Security forces entering the Temple mount: It is permitted for security forces to enter the Temple Mount area, and even the Kodesh Hakedoshim, in order to prevent a life-threatening situation, such as to fight Arab terror which commonly occurs on the Temple Mount. Nonetheless, being that in many cases, the police send units up even during times that are free of danger, therefore a G-d fearing Jew is not to accept such a position. Commonly, due to this reason, there is a high percentage of non-Jewish soldiers who patrol the area, in order to avoid religious conflict.
Gedolei Yisrael from all spectrums of Jewry prohibit visitation to the Temple Mount, including to those areas which have been determined to not be part of the Halachic Har Habayis and are not restricted in entry.
The Rebbe’s approach:
In a letter to Rabbi Meir Yehuda Geitz, the chief Rabbi of the Kosel, the Rebbe stated as follows:
It is obvious that in the current state of affairs in which the public is waring from right to left [further away from Torah] that I am most vehemently against even the mere public discussion of the question of allowance to enter Har Habayis. [The reason for my absolute opposition is] because the moment that this discussion would begin, a number of people will visit the area, including the areas which are certainly prohibited, G-d save us, and that number will continue to grow, G-d have mercy on us. All the warnings about this issue (assuming they would be issued) will simply ignite the inclination of those people and increase the amount of people who go. Whoever brings up or participates in the discussion of this issue, and certainly one who actually goes up to Har Habayis, in addition to the sacrilege of the elders of Jerusalem, and the city of Jerusalem, it is sacrilege of the Har Habayis itself. Upashut!
May one fly over the Har Habayis area?
No. This prohibition applies likewise to a drone.
 Admur 94/1 in parentheses; M”A 560/2; Rambam Beis Habechira 6; Sefer Hateruma; Aguda; Semag; Chinuch; Ritva; Tashbatz; Kaftor Vaferach 6; Yireim 325 Tur; M”B 560/5; Likkutei Halachos Zevachim; Binyan Tziyon 2
Other opinions: Some Poskim rule that in today’s times, during exile, there is no longer a Kareis prohibition involved in entering the restricted areas on the Temple Mount. [Raavad ibid, brought in M”A ibid] Practically, we do not rule like this opinion. [M”A ibid; Binyan Tziyon ibid] Furthermore, there is room to learn that even according to the Raavad there is a prohibition involved. [However, see Radbaz 691]
 Rambam Hilchos Bias Hamikdash chapter 2-3
 See Pesachim 68a; Tamid 27b; Rashi Yevamos 7b and Zevachim 32b; Tosafus Yuma 6a; Rosh Nazir 44b; Ritva Yevamos 7b; Meiri Yevamos 3b; Yireim 277 and 391; Semag 304
Other opinions: Some Poskim rule a Baal Keri is permitted to enter the Har Habayis. [Omitted from Rambam Hilchos Beis Habechira 7/15; Bais Hamikdash 3/3; and implied from Shevisas Asur 3/3; Aruch Hashulchan Hasid 36/10 concludes this to be the view of the Rambam]
 Rambam 3/3
 Rambam 3/4
 Rambam ibid 3/8
 Rambam ibid 3/5-6
 Rambam ibid 2/4
 Rambam ibid 2/1-2
 Rambam ibid 2/4
 Rambam ibid 2/1
 Rambam ibid 2/3
 See Ir Hakodesh Vihamikdash 4/1
 Midos 2
 Today’s Temple Mount is no longer square and has the following measurements: From East to West: 321 meters by its Northers side and 283 Meters by its southern side, for an average of 302 Meters; From North to South is 490 by its Western side and 482 meters by its Eastern side, for an average of 482 Meters. There is thus an approximate total of 180 extra meters in today’s Har Habayis. [See Ir Hakodesh Vihamikdash 4/1-2] The Eastern wall is 465 meters; the western wall is 488 meters; the northern wall is 317 meters; the southern wall is 275 meters
 Some say it is found by the rock that is under the Dome of the rock. [Radbaz 691; Ir Hakodesh Vihamikdash 4/4; All Poskim brought in later footnotes] Others say the rock is the area of the Mizbeaich. [See Ir Hakodesh Vihamikdash 4/4 who negates this position] Others say the Kodesh Hakedoshim is in the Southern area of the Har Habayis. [Kaftor Vaferach]
 Some say it is 48 cm [Shiureiy Torah p. 249; Daas Torah 35/116] Others say it is 53 cm [Darkei Teshuvah 19] Others say 54 cm [Aruch Hashulchan Y.D. 201] Others say 57 cm [Meishiv Davar 24] Others say 58 cm [Chazon Ish in Kuntrus Hashiurim 39/5; End of Kitzur SHU”A] 60 cm [Ir Hakodesh Vihamikdash 4/1-3] 63 cm [Darkei Teshuvah in name of Chasam Sofer 181; Levush Mordechai 133]
 Radbaz 691; Chida in 561; Chasam Sofer Y.D. 236; Chofetz Chaim Yalkut Halachos Zevachim p. 34; Chazon Ish E.H. 107; See Bach 561/5; Ir Hakodesh Vihamikdash 4/4; Pirkei Derebbe Eliezer end of chapter 30 [omitted from some Nuschaos] “Bnei Yishmael will build a building on the Heichal; The following historians: Bordo [year 333]; Eutychias [year 876]; Binyamon Todelo [year 1170]; Rav Pesachya Mirogenshburg; See Sefer Chatzors Beis Hashem of Rav Menachem Koran
 Midos 5/1; Radbaz ibid
 Midos 2
 There were 11 Amos between the western wall of the Heichal and the wall of the Azara/Beis Hamikdash. [Radbaz ibid] However see that there were 10 Amos from the walls of the Beis Hamikdash to the Cheil. [Mishneh Midos 2/3]
 See Piskeiy Teshuvos 561/5
 Radbaz ibid; Meiri Shavuos 16a; However see Minchas Yitzchak 5/1; Yabia Omer 5/26; Tzitz Eliezer 10/1
 Radbaz ibid [brought in Shaareiy Tehsuvah 561/1] defends going on certain steps even though it is possibly part of the section of the restricted area, as a) Maybe it is not part of the restricted area and b) Even if it is, perhaps the air of the Azara was never made holy, and c) Perhaps we rule like the Raavad who holds there is no Kareis today involved in entering the Makom Hamikdash.
 Minchas Yitzchak 5/1; Yabia Omer 5/26; Tzitz Eliezer 10/1; Rav Elyashiv; Rav Wozner; Rav SZ”A; Rav Zevin; Rav Yaakov Landa; Rav Kook; Rav Mordechai Eliyahu; Rav Avinar; Chief Rabbi’s of Israel in their respective terms including Rav Kook
 Rebbe ibid
 Heard from Harav Yaakov Yosef
 Printed in Menachem Meishiv Nafshi Erech “Rav Geitz”
 Yabia Omer 5 Y.D. 26-9; Kinyan Torah 3/58; Piskeiy Teshuvos 561/5
 The reason: As the air over the Azara was sanctified and it is prohibited for a Tamei person or item top enter that area. [ibid; See Rambam Bias Hamikdash 3/19; See Radbaz ibid that it is a doubt if the air of the Azara was made holy.]