Al-Masjid al-Nabawi often called the Prophet's Mosque, is a mosque built by the Islamic Prophet Muhammad situated in the city of Medina. It is the second holiest site in Islam (the first being the Masjid al-Haram in Mecca). It was the second mosque built in history and is now one of the largest mosques in the world. After an expansion during the reign of al-Walid I, it also now incorporates the site of the final resting place of Muhammad and early Muslim leaders Abu Bakr and Umar.

The site was originally adjacent to Muhammad's house; he settled there after his Hijra (emigration) to Medina in 622. He shared in the heavy work of construction. The original mosque was an open-air building. The basic plan of the building has been adopted in the building of other mosques throughout the world.

The mosque also served as a community center, a court, and a religious school. There was a raised platform for the people who taught the Quran. Subsequent Islamic rulers greatly expanded and decorated it. In 1909, it became the first place in the Arabian Peninsula to be provided with electrical lights. The mosque is under the control of the Custodian of the Two Holy Mosques.

One of the most notable features of the site is the Green Dome in the south-east corner of the mosque, originally Aisha's house, where the tomb of Muhammad is located. In 1279 AD, a wooden cupola was built over the tomb which was later rebuilt and renovated multiple times in late 15th century and once in 1817. The dome was first painted green in 1837, and later became known as the Green Dome.

The mosque is located in what was traditionally the center of Medina, with many hotels and old markets nearby. It is a major pilgrimage site. Many pilgrims who perform the Hajj go on to Medina to visit the mosque and the Prophet. The mosque is open for service 24/7, all year round.