The Taj Mahal complex includes the tomb, a mosque, and a guest house.
The guest house stands on the eastern side of the marble mausoleum, opposite the mosque on the west. Known as the jawab, meaning “answer,” it was designed mainly to preserve the complex’s visual symmetry. Its exterior closely resembles the mosque, although it lacks features needed for congregational prayer, such as a mihrab.
The tomb is the complex’s centerpiece, while the mosque and guest house balance it on either side of the great platform. The mosque could serve worshippers, and the jawab may have offered accommodation or space for important visitors. This arrangement reflects the Mughal taste for carefully planned symmetry.
A common mix-up is to treat the guest house as another religious building or to call both flanking structures mosques. Only the western building is the mosque; the eastern counterpart is the guest house.