Undoubtedly, Delhi’s culture has been impacted by its history and the fact that it has served as the capital of the nation for more than a century. Today, it has become a melting pot because of continued migration of people from all over India. Its diverse cultural past is also evident in its heritage buildings and historical monuments. The Archaeological Association of India recognizes 1,200 heritage buildings and 175 monuments as national heritage sites in Delhi. The Old City is adorned by Jama Masjid (India's largest mosque) and the Red Fort. Delhi is, in fact, the location of three World Heritage Sites: the Red Fort, Qutb Minar, and Humayun's Tomb. Other noteworthy monuments of exemplary architectural wonder include the India Gate, the Jantar Mantar (an eighteenth-century astronomical observatory), and the Purana Qila (a sixteenth-century fortress). Raj Ghat is the memorial site of Mahatma Gandhi. New Delhi also houses several government buildings and official residences reminiscent of British colonial architecture, including the Rashtrapati Bhavan, the Secretariat, and Rajpath, the Parliament of India.