Visiting graves is Sunnah in all places, especially visiting al-Baqee’ where many of the Sahaabah (may Allaah be pleased with them) are buried, including Ameer al-Mu’mineen ‘Uthmaan ibn ‘Affaan (may Allaah be pleased with him). His grave is there and is well known.
Similarly it is Sunnah to go out to Uhud and visit the graves of the martyrs there, including Hamzah ibn ‘Abd al-Muttalib, the paternal uncle of the Messenger of Allaah (peace and blessings of Allaah be upon him). One should also visit the Mosque of Quba’, going out with wudoo’ and praying two rak’ahs there, because there is great virtue in doing so. The Messenger of Allaah (peace and blessings of Allaah be upon him) said: “One prayer in the Mosque of Quba’ is like ‘Umrah.” Saheeh al-Targheeb, 1180. And he (peace and blessings of Allaah be upon him) said: “Whoever purifies himself in his house, then comes to the Mosque of Quba’ and offers a prayer there, will have a reward like that of ‘Umrah.” Saheeh al-Targheeb, 1181.
There is nothing to be visited in Madeenah apart from the following: the Mosque of the Prophet, the grave of the Prophet (peace and blessings of Allaah be upon him), al-Baqee’, the martyrs of Uhud, and the Mosque of Quba’. There is no basis for visiting any other places such as the Seven Mosques and Masjid al-Ghamaamah, and going to them with the intention that this is an act of worship is bid’ah (an innovation), because that was not narrated from the Prophet (peace and blessings of Allaah be upon him). No one should suggest that a particular time or place or action or action has a special virtue or is a means of drawing closer to Allaah without evidence from sharee’ah.