This is the tomb of Ibrahim (Peace be upon him), built right above his real grave, which is located underground. On the left side is a window from the Jewish synagogue, which is built right next to the mosque. This place is a source of great friction between Muslims and Jews and is carefully guarded.
Ibrahim (peace be upon him) is mentioned by name 69 times in the Quran. He is known as "Khalil-Ullah", the friend of Allah. Ibrahim (peace be upon him) is considered the patriarch of the three great monotheistic faiths, Judaism, Christianity and Islam.
Almighty Allah said in the Qur'an in Surah al-Imran: [Quran 3: 65-68]
"O people of the Scripture (Jews and Christians)! Why do you dispute about Ibrâhim (Abraham), while the Taurât (Torah) and the Injeel (Gospel) were not revealed till after him? Have you then no sense?
Verily, you are those who have disputed about that of which you have knowledge. Why do you then dispute concerning that which you have no knowledge? It is Allâh Who knows, and you know not.
Ibrâhim (Abraham) was neither a Jew nor a Christian, but he was a true Muslim Hanifa (Islâmic Monotheism - to worship none but Allâh Alone) and he was not of Al-Mushrikûn (See V.2:105)."
Ibrahim (Peace be upon him) died at the age of 175 years.
Yahya bin Said bin al-Musayyub said: “Ibrahim, (may Allah bless him), was the first to give hospitality to the guest and the first person to be circumcised and the first person to trim the moustache and the first person to see grey hair. He said, ‘O Lord! What is this?’ Allah the Blessed, the Exalted, said, ‘It is dignity, Ibrahim.’ He said, ‘lord, increase me in dignity!“