Wadi-us-Salaam (Valley of Peace) is the largest Islamic cemetery, and one of the largest cemeteries in the world. Located in Najaf, Iraq, this cemetery holds the graves of many Prophets, and is located near the Holy Tomb of Hazrat Imam Ali ibn Abu Talib (as).

The cemetery covers 1485.5 acres (6 km²) and contains approximately 5 million bodies.

Prophet Ibrahim (as) had come to this place along with Prophet Ishaq (as). The people were most eager for them to make Najaf their permanent dwelling-place. Ibrahim (as) agreed to do so on condition that they would sell him the valley behind the village for cultivation. Ibrahim (as) said that a time would come when there would be a tomb there with a shrine, at which seventy thousand people would gain absolutely undisputed entrance to Paradise, and would also be able to intercede for many others. And so as per the prediction of Ibrahim (as), Imam Ali (as) was buried within the vicinity.
It is related on the authority of the Fourth Holy Imam, Imam Sajjad (as) that Imam Ali (as) once said that:

"This Valley of Peace is part of Heaven and that there is not a single one of the believers in the world, whether he dies in the East or West, but his soul will come to this Paradise to rest. As there is nothing hidden in this world from my eyes," Maula Ali ('a) went on to say, "I see all the believers seated here in groups and talking with one another."

Wadi-us Salaam:
Those buried here include:
Tomb of Prophet Hud (as)
Tomb of Prophet Saleh (as)
Maqam of Imam Ja'far al-Sadiq (as)
Maqam of Saheb al-Asr, Imam Al-Mahdi (as)
Mosalla of Imam Ali Zayn al-Abidin (as)

وادي السلام