All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The grave of the Prophet was concealed and it was not raised above the ground. The Muslims surrounded it by three high walls in order to prevent people using the grave as a mosque or even as a Qiblah (direction) for people to face when praying. 'Aa'ishah narrated that when the last moment of the life of the Messenger of Allaah came he started putting his Khameesah (cloth) on his face and when he felt hot and short of breath he took it off his face and said: "May Allaah curse the Jews and Christians for they built the places of worship at the graves of their Prophets." The Prophet was warning (the Muslims) against what they had done.
'Aa'ishah said, "Had it not been the fear of making the grave of the Prophet a place of worship it would have been open for everyone". Thus, the fear that people would give the grave more importance than that which is permissible, spurred the Companions of the Prophet to level the grave to the ground. Then the Muslims elevated the walls even higher and closed all the gates leading to them. Then, fearing that some people might pray facing the grave, they built two more walls on the two northern corners of the grave constituting a tri-dimensional angle so that nobody could face his grave while praying. On the other hand, there is no need to stand on his grave, as invoking blessings on him can be done from any place in the world. Abu Daawood reported from Abu Hurayrah that the Prophet said: "Do not make your houses graves, and do not make my grave a place of festivity. But invoke blessings on me, for your blessings reach me wherever you may be."
As far as we know, there are no pictures of the grave itself.
Allaah Knows best.