medina is very important to muslims. this is because the prophet muhammad is buried in a mosque known as 'masjid-e-nabawi' or 'the mosque of the prophet'. the mosque was built on a site next to muhammad's home. muslims believe that prophets must be buried at the very same place that they die. accordingly, muhammad was buried in his house. the tomb later became part of the mosque when it was expanded by the umayyad caliph al-walid i. the first mosque of islam is also in medina. it is known as "masjid quba," (the quba mosque).