To the east of the Taj mausoleum, opposite to the mosque, this red standstone structure is almost a mirror image of the Taj mosque.
It is also known as the mehman khanna and as jawab(answer). It is not used for prayer purposes as it does not face the Mecca.
The exact purpose of this building is not known, though it might have been built just to preserve the symmetry of the Taj.
It may also have been used as a guest house during death anniversaries of Mumtaj mahal by the visitors.
Floor between this structure and the mosque also depicts a full size drawing of the bronze pinacle on top of the Taj mausoleum.