What exactly constitutes the 'Masjid al-Aqsā'?
There has been a lot of confusion and even some controversy regarding the specific area demarcating the Masjid al-Aqsā. And every time someone posts a picture of the iconic 'Dome of the Rock', they get bombarded with well-intentioned commentators who say that this is a huge mistake, and that the 'Masjid al-Aqsā' is not the Dome of the Rock but rather the masjid south of it. This enthusiasm, while praiseworthy in its essence, is misplaced.
The fact of the matter is that the term 'Masjid al-Aqsā' is actually the entirety of what is known as the 'Aqsa Complex' [or what is known in Jewish circles as the 'Temple Mount'], and includes many structures within it (see pictures). The Aqsā Complex is a large area that is roughly 37 acres - all of this comes under Masjid al-Aqsā.
In fact, the walls that demarcate the boundaries of the complex do not actually imply that the sacredness finishes beyond those wall - rather, the entirety of the area, and even city, is blessed and sacred. The Quran mentions that the land itself is blessed (الأرض التي باركنا فيها), and even the land around it (باركنا حوله). For logistical purposes, clearly a 'line' needs to be drawn where a masjid ends and residence areas begin - but that is for our own living purposes. In the Shariah, that region is holy, and the 'Masjid al-Aqsā' term, is not defined by what we humans have done by building a complex or a few structures.
All of the ḥadīth literature, and sīrah works, and early history books, refer to Masjid al-Aqsā as being in Jerusalem. In a Muttafaq `alayhī hadith, we are told that only three masjids can be traveled to: Masjid al-Ḥarām, the Prophet ﷺ's masjid, and Masjid al-Aqsā. It is explicitly mentioned that the Companions who entered Jerusalem thanked Allah for being allowed to pray in 'Masjid al-Aqsā'.
When Umar (r) traveled to Jerusalem, according to all historical works, he himself prayed Jum'ah at the periphery of what is today the Complex, and demarcated a small masjid (which is known as Masjid Umar) that was the southernmost part of what the Christians considered the original location of the temple, and which they had abandoned, as they didn't consider it holy. This area was directly east of the remnants of Herod's Temple, now known as the Wailing Wall. Later, the Umayyads added to this masjid and constructed a larger masjid out of bricks - this is called the Marwānī Masjid, after the Caliph Marwān b. al-Ḥakam (d. 685 CE). This structure continued to expand, and some began calling it al-Aqsā Masjid, simply because it was and remains the largest, and first, masjid within the Aqsā Complex. It is also called Masjid al-Qibalī because it is the one that is on the qibla-side of the complex.
The Caliph Abd al-Malik b. Marwān (d. 705 CE) was the one who built the magnificent structure of the Dome of the Rock behind the Marwānī masjid. Many parts of the current structure are original, and it is one of the oldest original structures of Islam still standing today. The Dome of the Rock houses the iconic small mountain that was a prominent feature of the Complex (and from which, according to folklore, the Prophet ﷺ was taken up - in actual fact we do not know the precise location from within the Complex where the ascension began).
Throughout the course of history, many more structures and rooms were built within the Aqsā complex, and any video will show you the many dozens of constructions and trees and libraries.
The claim that is held by some non-Sunnī groups that the Quranic term 'Masjid al-Aqsā' is a holy place in the heavens, and not on earth, is baseless and does not emanate from within the mainstream Sunnī tradition. Also there is clearly an element of animosity from these groups for Umar (r) and the Umayyads that fuels this eccentric belief. It is incontrovertible that the Companions and early Muslims all understood that Masjid al-Aqsā is in the city of Jerusalem.
To summarize: the Quranic term 'Masjid al-Aqsā' does NOT apply only to one structure within the complex (including, confusingly enough, the structure commonly called al-Aqsa Masjid) and instead refers to the entirety of the complex, and even beyond. Hence, it's really not a mistake to show a picture of a part of the complex as Masjid al-Aqsa, we just need to teach the people that the entirety of the complex is sacred and a part of our history.
[Copied from Sh. Dr. Yasir Qadhi's Facebook post]