 The western building is a mosque and the other is the "jawab" (answer), thought to have been constructed for architectural balance although it may have been used as a guesthouse.Distinctions between the two buildings include the "jawab's" lack of a "mihrab" (a niche in a mosque's wall facing Mecca), and its floors of geometric design whereas the floor of the mosque is laid with outlines of 569 prayer rugs in black marble.The mosque's basic design of a long hall surmounted by three domes is similar to others built by Shah Jahan, particularly the "Masjid-i Jahān-Numā", or Jama Masjid, Delhi.