Gemara

Mishnah: Once the Mikdash was built in Yerushalayim, Bamos were prohibited and were never permitted again. This was the "Nachalah".

Tana'im argue about whether or not Kedushas Yerushalayim still applies.

(Mishnah (Eduyos 8:6) - R. Eliezer): I heard that when they were building the Mikdash, they made curtains for (the areas that will be enclosed by) the Heichal and the Azarah. The Heichal walls were built outside its curtains. The Azarah walls were built inside its curtains.

R. Yehoshua: I heard that we may offer Korbanos even without a Mikdash, eat Kodshei Kodoshim even without curtains, and eat Kodshim Kalim and Ma'aser Sheni, even though there is no wall (around Yerushalayim), because Kedushas Yerushalayim was permanent.

Inference: R. Eliezer holds that (curtains were needed because) the Kedushah ceased!

Objection (Ravina): Perhaps both hold that the Kedushah was permanent. Each Tana said what he heard.

According to R. Eliezer, we must say that the curtains were merely for Tzni'us (places of Kedushah should not be so exposed).

The Tana'im of the following two Beraisos argue about whether or not the Kedushah ended:

Beraisa #1 - R. Yishmael b'Rebbi Yosi: These cities (in the Mishnah Erchin 32a) were listed because the exiles who returned (from Bavel) were Mekadesh them. The first Kedushah lapsed from the time of the Churban.

This shows that he holds that the Kedushah was not permanent.

Contradiction (Beraisa #2 - R. Yishmael b'Rebbi Yosi): If you have a tradition that a city had a wall from the days of Yehoshua, all laws of walled cities apply to it, for the Kedushah was permanent.

Resolution #1: The Tana'im argue about the opinion of R. Yishmael b'Rebbi Yosi.

Resolution #2: The Tana of Beraisa #2 is really R. Eliezer bar Yosi.

(Beraisa - R. Eliezer bar Yosi): "Asher Lo Chomah" - ("Lo" has a superfluous Aleph, to include) even if it does not have a wall now, if it once had one.

Zevachim 107b - R. Yochanan: If one offers Korbanos outside the Mikdash nowadays he is liable, because the first Kedushah was permanent.

Reish Lakish: He is exempt. The first Kedushah was temporary (it ended after the Churban).

Yevamos 82b - Beraisa - Seder Olam: "That your fathers inherited, and you will inherit" - there is a first and second inheritance, not a third (the second Kedushah never ceased).

R. Yochanan: R. Yosi taught Seder Olam.

Shevu'os 14a - Mishnah: To add onto Yerushalayim or the Azarah, we need a king, a Navi, the Urim v'Tumim... If an addition was made without all this, one who enters there (b'Tum'ah) is exempt.

16a - Rav Huna: This is the correct text.

Rav Nachman: The text should say, if an addition was made without (at least) one of these (he is exempt, for it does not get Kedushah).

(According to Rav Huna, Ezra could not Mekadesh Bayis Sheni, since they lacked the Urim v'Tumim.) Rav Huna must hold that Shlomo's Kidush of the Mikdash was permanent. Ezra's actions were only a commemoration of Kidush.

Rav Nachman holds that the Kedushah of the first Mikdash had ceased. (According to his text, Ezra was able to Mekadesh Bayis Sheni, even without the Urim v'Tumim.)

Rishonim

Question (Tosfos Shavu'os 16a DH Teni): What forced Rav Nachman to change the text? In any case some Stam Mishnayos hold that the first Kedushah was permanent!

Rambam (Hilchos Beis ha'Bechirah 1:3): Once the Mikdash was built in Yerushalayim it was forbidden to build a house for Hash-m for bringing Korbanos anywhere else. The Beis ha'Mikdash for all generations is only in Yerushalayim, in Har ha'Moriyah - it says "Zeh Beis Hash-m" and "Zos Menuchasi Adei Ad".

Rambam (ibid. 6:14,15): Shlomo gave permanent Kedushah to the Azarah and Yerushalayim. Therefore, we may offer Korbanos even when the Bayis is not built, and we may eat Kodshei Kodoshim in the entire Azarah even though it is not surrounded by a wall. We may eat Kodshim Kalim in Yerushalayim even though there is no wall, because the first Kedushah was permanent.

Even though the Kedushah of Eretz Yisrael regarding Shemitah and Ma'aseros was temporary, the Kedushah of the Azarah and Yerushalayim was permanent, because their Kedushah is the Shechinah, which is not Batel. It says "V'Hashimosi Es Mikdesheichem".

Source (Teshuvas Kol Mevaser 2:10 DH v'Od): R. Acha (Shemos Rabah 2:2 DH Moshe) says that the Mikdash remains in its Kedushah after the Churban, and that Shechinah never left the Western Wall.

Rambam (ibid.): The Mitzvos of Shemitah and Ma'aseros depend on conquering the land, so once the Nochrim took it, the conquest (by Yisrael) was Batel, so it was no longer considered Eretz Yisrael. Ezra did not Mekadesh Eretz Yisrael through conquest, rather, through Chazakah. Therefore, any place where Olei Bavel settled and Ezra was Mekadesh is still Kodesh nowadays, even though the land was taken.

Rebuttal (Ra'avad): The Rambam says his own reasoning without a source. Many Gemaros says that if there is no Mikdash, we must leave Kodshim to rot. It is clear from Bava Metzi'a 53b that if the Mechitzos fell, Ma'aser Sheni may not be eaten. We do not distinguish the Kedushah of Eretz Yisrael from that of Yerushalayim.

Radvaz: The Rambam (Pirush ha'Mishnayos Eduyos 8:6) says that all agree that Shlomo's Kidush of Bayis Rishon was permanent. The argument is only about the rest of Eretz Yisrael. This is like Rav Huna. If the Ra'avad questions the Rambam's reason (the Shechinah is not Batel), this is explicit, "Veha'Shimosi Es Mikdesheichem" (even when they are desolate, they are Kodesh - Megilah 28a). Perhaps the Ra'avad asks why the Rambam rules against Rav Nachman.

Kesef Mishneh: The Halachah follows R. Yehoshua against R. Eliezer, and Yehoshua holds that the Kedushah is permanent. Also, we follow R. Yochanan against Reish Lakish (Zevachim 107b). Also, the Gemara suggests that perhaps all agree that the Kedushah is permanent. R. Yehoshua said that the Kedushah of Yerushalayim and the Mikdash is permanent. He did not say so about the Kedushah of Eretz Yisrael. However, I have no answer for the question from the Gemaros that say that if there is no Mikdash, we must leave Kodshim to rot.

Teshuvas Mishpat Kohen (Inyanei Eretz Yisrael 96 DH Yesod): We follow the Mishnah in Eduyos (brought in Megilah 10a) against all other Mishnayos. Since it is possible to learn that R. Yehoshua and R. Eliezer agree (that the Kedushah was permanent), like Ravina, we do so.

Radvaz: The Rambam holds that if the Mikdash would be standing, one could eat Ma'aser Sheni and Revai even after the wall of Yerushalayim fell. Even though the Kedushah of Yerushalayim is permanent, one may not eat without a Mikdash.

Ra'avad: Further, even R. Yosi, who says that the second Kedushah was permanent (Yevamos 82b) says so only about the rest of Eretz Yisrael, but not regarding Yerushalayim. This is because Ezra knew that Hash-m would later make a permanent Kedushah. One who enters there nowadays is not Chayav Kares.

Kesef Mishneh: The Ra'avad gives no source that R. Yosi refers only to the rest of Eretz Yisrael. Why wouldn't Ezra make a permanent Kedushah, to allow Korbanos after the second Churban? The Ra'avad seemed like he was unsure. Why does he exempt from Kares?

Radvaz: Even if Ezra knew that Hash-m will later make a permanent Kedushah, Ezra could have been Mekadesh now, and Hash-m would add in area and quality of the Kedushah later! Further, according to Rav Huna Ezra was unable to Mekadesh, and according to Rav Nachman he did Mekadesh! Rather, the Ra'avad must hold like Rav Nachman that Ezra was Mekadesh. He was Mekadesh Eretz Yisrael Stam; such Kidush is permanent. He limited the Kedushah of Yerushalayim and the Mikdash to when they stand, to allow Hash-m to Mekadesh them later!

R. Shimshon (Shevi'is 6:1 b'Sof): It is not difficult to say that Kedushas ha'Aretz is Batel for Terumah, but Kedushas Mechitzos (of the Mikdash, to Mechayev for Shechutei Chutz) remains. Perhaps we learn from "Asher Lo Chomah" - if it once had a wall, even if now there is no wall. Alternatively, "Zeh Menuchasi Adei Ad" teaches that there is no Heter Bamos after Yerushalayim.

Sefer Yere'im (277 (325 in old edition)): The Halachah follows R. Yosi who says that the Kedushah of Eretz Yisrael is permitted. All the more so the Kedushah of Yerushalayim, which is greater, is permanent. R. Yishmael b'Rebbi Yosi holds that Kedushas ha'Aretz was Batel; we learn from this that Kedushas Yerushalayim was Batel, to be lenient (Shevu'os 16a). All the more so we may learn a stringency, that the opinion that Kedushas ha'Aretz was not Batel says the same about Yerushalayim! Therefore, nowadays one must be careful not to enter Makom ha'Mikdash, since we are Temei'im.

Note: If it is more reasonable that Kedushas Yerushalayim is permanent, how can the Gemara learn the other direction? Perhaps it is reasonable that the same law applies to both. The Yere'im says that if it is possible to distinguish, Kedushas Yerushalayim would be more permanent. The Gemara is so confident that they are the same that it learns a leniency from this (even though there was a reason to say that Yerushalayim is more permanent). All the more so we may learn a stringency!

Tosfos (Makos 19a DH v'I): The Gemara forbids eating Ma'aser in Yerushalayim after the Churban. We must say that even though Kedushas Mikdash was not permanent, Kedushas ha'Aretz was permanent.

Poskim

Tur (YD 331): We should be able to eat Ma'aser Sheni in Yerushalayim today. Even though there is no wall, the Kedushah of the city and the Beis ha'Mikdash are not Batel. However, a Hekesh equates Ma'aser to Bechor, to teach that it can be eaten only when there is a Mizbe'ach.

Magen Avraham (OC 561:2): The Rambam had the text of Tosfos (Makos 19a DH v'I), that even according to the opinion that Kedushas ha'Mikdash was permanent, one may not eat Bechor and Ma'aser nowadays. One who enters the Mikdash nowadays is Chayav Kares. Also the Agudah says so.

Likutei Halachos (Zevachim p. 66b, and Zevach Todah): Many Rishonim agree with the Rambam; the Ra'avad is a lone opinion. Also, R. Eliezer ben Yakov (Zevachim 62a) permits Hakravah without a Mikdash (because the first Kedushah was permanent), and the Halachah always follows him, even in a Beraisa.

Kaf ha'Chayim (8): It is permitted to come close to the openings to the Mikdash and enter the Aliyos around the Mikdash.