Are there any authentic Hadith reported concerning the virtue of visiting the grave of the Prophet (peace and blessings be upon him)?

There is no authentic hadith specifically about the virtue of visiting the Prophet's grave (peace be upon him). The narrations on this matter are weak or fabricated. Al-Hafiz Ibn Hajar mentioned that all their chains of transmission are weak, and Shaykh al-Islam Ibn Taymiyyah stated that they are all fabricated. Visiting the Prophet's grave (peace be upon him) falls under the general hadiths that recommend visiting graves for men, such as his (peace be upon him) saying: "I had forbidden you from visiting graves, but now visit them, for they remind you of the Hereafter." العلامة Ibn Baz holds that visiting the Prophet's grave (peace be upon him) is neither obligatory nor a condition for Hajj; rather, it is recommended for those who visit the Messenger's mosque or are close to it. As for those far away, they should not undertake a journey specifically to visit the grave, but it is legislated for them to undertake a journey with the intention of visiting the Noble Mosque.