There is an empty grave next to the Prophet Muhammad intended for Jesus after he returns.

As you likely know, Muhammad was an Islamic prophet and messenger of God, and is seen by Muslims to be the last prophet sent by God for mankind. He is considered by some to be the founder of Islam, and to be the restorer of the uncorrupted faith of the other prophets sent by God before him. Muhammad’s grave lies within the confines of what used to be the house of him and his wife, Aisha. 

During his lifetime it was adjoined to a mosque, and after his death it was expanded further to include his tomb. The mosque and tomb are traditional visits for Muslims undergoing the pilgrimage to Mecca. 

Muhammad is buried next to Abu Bakr and Umar, the first two caliphs, and beside Muhammad’s tomb is an empty grave reserved for Jesus. According to Quran commentator Baidawi, when Jesus returns to kill the antichrist, he (Jesus) will be buried next to Muhammad there. 

(Source)