Enhancing the already present splendor of the Taj Mahal is a building that stands on the western side of it, a Mosque made up of red sandstone. It serves two purposes, first, it was obligatory according to the Muslim law for each mausoleum to have a place of worship nearby; second, the mosque and a mirror image of the mosque, a guest house that stands on the opposite side of it, together provide a perfect symmetrical balance to the architecture of whole of Taj Mahal. Used for prayer purpose, the mosque faces the direction of the holy city of Mecca and is believed to have been built by Isa Mohammad. The exterior possesses one dominant portal known as an Iwan and on either side of it are two smaller arches. Three marble coated domes and four little domed kiosks with marble veneer make up for the splendid visuals of the mosque, a design that is similar to others built by Shah Jahan, particularly to his Masjid-Jahan Numa, or Jama Masjid, Delhi.
The interiors host an elegantly designed floor that is made up of a material that appears to be velvet red in shade and is in the shape of clearly defined prayer mats, 569 prayer mats in total. The interiors of the mosque are inscribed with delicate calligraphy citing the name Allah and quotations from scriptures (taken from Sura 91, The Sun, taken from the holy book of Quran). However, the main feature of the mosque that distinguishes it from the opposite structure of the guest house is the presence of Mihrab and Minbar. The Mihrab is an indented enclosure that indicates the direction of Mecca and the direction which the Muslims face to perform their prayers or salat. The place from where the priest delivers a speech is known as Minbar and is always positioned to the right hand side of the Mihrab and consists of three steps to a flat platform.
Additionally, there lies a small stone enclosed space of 19 ft by 6.5 ft, which had served as a temporary grave where the remains of Mumtaz Mahal were kept for some time when they were first brought to Agra, until they finally found an eternal place of rest inside the beautiful mausoleum built in her precious memory. This enclosure is located along the western boundary wall that also houses the well of the mosque. Also, the exteriors of the mosque, crypt and cenotaphs carry pietra dura decoration of a fabulous unexcelled elegance. The name of Allah and verses from the Holy Qur’an has been used copiously all over the mosque. And the pool in front of the mosque functions as the place for ablution before the prayer. As Percy Brown, the noted art historian observes, the Taj “resembles the spirited sweep of a brush rather than the slow laborious cutting of a chisel”.