The mosque establishes the form that the Mihman Khana follows. It is based on a standard type which the Mughals took over from the Sultanate architecture of Delhi, namely that of an oblong massive prayer hall formed of vaulted bays or rooms arranged in a row with a dominant central pishtaq and domes. The elevation of mosque and Mihman Khana takes its cue from the great gate, the third monumental subsidiary building of the funerary garden (their relationship is also announced on the overall plan, where they form the points of a compositional triangle).
The mausoleum sits on a plinth, decorated with delicate relief carvings (munabbat kari) of plant elements. This type of ornament, conforming to the principles of sensuous attention to detail and selective naturalism, is reserved for the lowest zone of the building, where it could be immediately appreciated by the viewer. Naturalistic ornament also appears above the plinth, in the spectacular flowering plants of the dados of the pishtaq halls.
The Marble Platform of the Mausoleum (Takhtgah)
Monumental platforms housing the tomb chamber, above the actual burial, had been a prominent feature of Mughal mausoleums. The platform is square and its corners are accentuated by the four minarets which project as five sides of an octagon. It is set off from the paved surface of the terrace by paving with an interlocking pattern of white marble octagons into which are set fourpointed sandstone stars, surrounded by a border with alternating long and short cartouches, a lobed variant of the angular pattern that frames the garden walkways. In the centre of the southern side of the platform, towards the garden, arc two flights of stairs, partly covered by tunnel vaults, which provide the only access from the terrace up to the level of the mausoleum.
In the centre of the other three sides tripartite bait in the form of an open oblong room flanked by two square cells, all covered with coved ceilings, is set into the platform. The central room has three arched openings corresponding to the trefoil-headed blind arches, filled with jalis in the hexagonal pattern found everywhere in the complex; a small rectangular window is cut into the central jali. These cell reached through doors are used for storage, these rooms probably originally served visiting members of the imperial family as a place to retire and rest; or perhaps the Qur'an reciters stayed here when they were not on duty.
The Pishtaqs or Monumental Porches
The pishtaqs embrace two storeys, and in their back walls are superimposed arched doors, larger below and smaller above. Both doors are filled with a rectangular framework containing jalis formed of tiny hexagonal elements in a honeycomb pattern. The setting of the door on the ground floor echoes that of the outer pishtaq arch: it is framed with an inscription band, and its spandrels show a simpler version of arabesques. The door of the upper floor is integrated into the transition zone of the half-vault, formed of arches.
The marble dome that surmounts the tomb is the most spectacular feature is accentuated as it sits on a cylindrical "drum" which is roughly 23 feet high. Because of its shape, the dome is often called an onion dome. The top is decorated with a lotus design, which also serves to accentuate its height. The shape of the dome is emphasised by four smaller domed chattris (kiosks) placed at its corners, which replicate the onion shape of the main dome. Their columned bases open through the roof of the tomb and provide light to the interior. Tall decorative spires extend from edges of base walls, and provide visual emphasis to the height of the dome. The lotus motif is repeated on both the chattris and guldastas. The dome and chattris are topped by a gilded finial, which mixes traditional Persian and Hindu decorative elements.
The Minarets (Minar)
Four minarets each more than 130 feet tall, display the designer's penchant for symmetry is set at the corners of the platform of the mausoleum and complete the architectural composition. They were designed as working minarets, a traditional element of mosques, used by the muezzin to call the Islamic faithful to prayer. Each minaret is effectively divided into three equal parts by two working balconies that ring the tower. At the top of the tower is a final balcony surmounted by a chattri that mirrors the design of those on the tomb. The chattris all share the same decorative elements of a lotus design topped by a gilded finial. The staircase opens through rectangular doors onto the balconies, and windows providing light and ventilation. Although these are covered with grilles, the interior is full of bats, which makes the ascent difficult because they react with hysteria to a person's entrance. The minarets create a special aura around the mausoleum, and the Mughals interpreted them as mediators to the upper sphere. For Lahauri they were 'like ladders to the foot of the sky' and to Kanbo they appeared as 'accepted prayers from the heart of a pure person which have risen to heaven'. The minarets were constructed slightly outside of the plinth so that, in the event of collapse, (a typical occurrence with many tall constructions of the period) the material from the towers would tend to fall away from the tomb.
The Riverfront Terrace (Chabutra)
The terrace of the Taj Mahal is the most ambitious ever built in a Mughal riverfront garden scheme, unprecedented in size and decoration and one of the most impressive platforms in the history of architecture. Its full splendour is displayed towards the river, where it forms an uninterrupted red sandstone band 28 feet 6 inches high from the lowest visible plinth and 984 feet long, with elaborate decoration in relief and inlay work. The riverfront terrace was the first part of the Taj Mahal complex to be built. All the areas are differentiated by their paving in varying geometrical patterns of dark and light sandstone.
The Roof Terrace
Staircases covered by pointed barrel vaults lead from the ground floor to roof level. On the upper floor they set out from the corridors between the central hall and the two southern corner rooms, and emerge at the sides of the east and west pishtaqs. As in the great gate, there is a system of ventilation shafts. The terrace is dominated by the outer dome, which rises with its high drum like an independent tower in the centre. The transition zone between drum and dome is ornamented with a moulding with a twisted rope design in inlay. At its top is a crowning element formed of lotus leaves, which had become a standard motif of Indian Islamic architecture. From this rises a finial formed of superimposed gilded bulbs topped by a crescent.
The dome is surrounded by four chhatris which, as the Mughal historians tell us explicitly, form the third floor of the octagonal corner chambers, in the shape of octagonal pillared domed structures. The roof terrace is surrounded between the pishtaqs by a high parapet, and its corners are accentuated by the guldastas terminating the shafts on the corners of the mausoleum.
The Main Finial
The main finial was originally made of gold but was replaced by a copy made of gilded bronze in the early 19th century. This feature provides a clear example of integration of traditional Persian and Hindu decorative elements. The finial is topped by a moon, a typical Islamic motif whose horns point heavenward. Because of such placements on the main spire, it creates a trident shape, reminiscent of traditional Hindu symbols of Shiva.
The calligraphy on the Great Gate reads "O Soul, thou art at rest. Return to the Lord at peace with Him, and He at peace with you."