In the collection of Ahmad and Ibn Hibban, it is reported that the Prophet (sas) said:
"Verily among the most evil of Allah's creation are those to whom Qiyama comes while they are still alive, and those who take graves as places of worship."
In the collection of Malik, the Prophet is recorded as having said:
"O, Allah, do not let my grave become an idol after I am gone which is worshipped. The anger of Allah is intense at a people who take the graves of their prophets as places of worship."
Bukhari and Muslim narrate:
"Allah cursed the Jews and the Christians, they took the graves of their prophets as places of prayer (masajid)."
Allah said in His book about the associationist people of Nuh:
[They said: Do not forsake your gods, do not forsake Wadd, Suwaa', Yaghooth, Ya'ooq, and Nasr.] Qur'an 71/23
Ibn Abbas and others of the first generations reported about this verse:
"These "gods" (mentioned in the verse) were a righteous people among the people of Nuh. When they died, the people were devoted to their graves. Later, they made images of them and worshipped them. This was the beginning of idol worship."
So for fear of the fitnah that the pictures might cause, I removed the link. And as a side note, the picture that allegedly shows the grave of the Messenger is false. The grave of the Messenger and his two companions is flat and it isn't raised above the ground.