The Katra Masjid (also known as Katra Mosque) is a mosque and the tomb of Nawab Murshid Quli Khan built between 1723 and 1724. It is located in the north eastern side of the city of Murshidabad, in the Indian state of West Bengal. Its importance lies not only as a great centre of Islamic learning but also for the tomb of Murshid Quli Khan, who is buried under the entrance staircase. The most striking feature is the two large corner towers having loopholes for musketry. At present it is maintained and protected by the Archaeological Survey of India and the Government of West Bengal.
Source from : wikipedia.