Strict planning determines the organization of the garden component of the river front scheme, the cross-axial chahar bagh. The large square is divided by two main walkways (khiyaban) into four quadrants; each quadrant is in turn sub divided by narrower cross-axial walkways, so that sixteen sub-quadrants are formed; and the garden as a whole is surrounded by a walkway which connects with all the sub-walkways. Such geometrical patterning had been characteristic of early Mughal architectural decoration; in the Taj Mahal, when floral designs became the nobler form of ornament, it was demoted and used for floors and for jails.
At the crossing of the walkways in the centre of the garden is a raised platform (chabutra) of white marble with an ornamental pool (hauz) containing five fountains. Kanbo claimed eulogistically that it held the water of the celestial Kausar, the Propher's river in Paradise, which fills the pool at which believers bench their thirst on arrival. He also lauds the 'novel design' of the pool with its lobed and voluted corners. The four marble benches around the tank were put in 1907-08 on the order of Curzon. The four main walkways are identical, but they are differentiated through their context. The enclosing wall is lined by a peripheral walkway and articulated by large pointed arches which support a narrow elevated walk running in front of ornamental crenellations. These elements of fortification architecture give the garden wall substance and a character of display. At the place where the subsidiary walkway of the south-western quadrant meets the garden wall, a drinking fountain of a design 'in accord with its surrounding' was put up in 1909-10 by the British government 'for the use of soldiers and other visitors to the mausoleum'. It is not in use today.
In the north-western quadrant, near the north-west corner, is an enclosure supposed to mark the site where Mumtaz Mahal was first buried, before her body was moved to its final resting place inside the white platform of the mausoleum. The garden was supplied with water from the Yamuna through an aqueduct, this brought water up to the middle of the west wall, hence it was distributed through earthenware pipes. The fountain system of the central tank consisted of copper vessels connected through copper pipes with the main supply pipe. According to Colonel Rowlatt, who undertook their first repair in 1867, the earthenware pipes were embedded in solid masonry 6 feet underground.
Paradise Gardens (Charbagh)
The concept of the paradise garden was one the Mughals brought from Persian Timurid gardens. It was the first architectural expression they made in the Indian sub-continent, fulfilling diverse functions with strong symbolic meanings. Known as the charbagh, in its ideal form it was laid out as a square sub divided into four equal parts. The symbolism of the garden and its divisions are noted in mystic Islamic texts which describe paradise as a garden filled with abundant trees flowers and plants.
Water also plays a key role in these descriptions: In Paradise four rivers source at a central spring or mountain, and separate the garden by flowing towards the cardinal points. They represent the promised rivers of water, milk, wine and honey.
The centre of the garden, at the intersection of the divisions is highly symbolically charged and is where, in the ideal form, a pavilion, pool or tomb would be situated.
The tombs of Humayun, Akbar and Jahangir, the previous Mughal emperors, follow this pattern. The cross axial garden also finds independent precedents within South Asia dating from the 5th century with the royal gardens of Sigiriya in Sri Lanka which were laid out in a similar way.
Ms. Ebba Koch, Professor at the Institute of Art History in Vienna, Austria and a senior researcher at the Austrian Academy of Sciences is an architectural and art historian is the only scholar who has been permitted to take measurements of the complex. She has been working on the palaces and gardens of Shah Jahan for thirty years opines that for the tomb of Shah Jahan's late wife though, where the mausoleum is sited at the edge of the garden, a variant of the charbagh is suggested; that of the waterfront garden. Developed by the Mughuls for the specific conditions of the Indian plains where slow flowing rivers provide the water source, the water is raised from the river by animal driven devices known as purs and stored in cisterns.
A linear terrace is set close to the riverbank with low-level rooms set below the main building opening on to the river. Both ends of the terrace were emphasised with towers. The riverside terrace was designed to enhance the views of Agra for the imperial elite who would travel in and around the city by river.
Other scholars suggest another explanation for the eccentric siting of the mausoleum at the Taj Mahal complex. If the Midnight Garden to the north of the river Jumna is considered an integral part of the complex, then the mausoleum can be interpreted as being in the centre of a garden divided by a real river and thus is more in the tradition of the pure charbagh.
The waterworks, which brought water to the Taj garden from the Yamuna by means of an aqueduct supported on arches, are situated outside its western wall and still preserve their original design. The inlet from the river is no longer visible (a temple complex dedicated to Shiva, now called Khan Alam Basai Ghat Mandir, has been built over it). From it a channel conducted the water into an oblong reservoir sunk into the ground along the east wall of a rectangular building containing storage tanks (now ruined). From-the reservoir the water was lifted by means of animal hides attached to pulleys, or Persian wheels turned by bullocks, to tanks at the top of the building. This fed an open channel along the top of the aqueduct wall.
The large aqueduct runs south, with two bends, up to the level of the western garden-wall pavilion. Here it turns east and forms a wider arm with three tanks on its top and meets the garden wall. The water was then conducted in a pipe through the wall and down to the level of the channels in the walkways of the garden. The wall is here 9.47 m (31 ft) tall, and the drop gave the water the necessary pressure to keep the fountains playing and the garden plots irrigated. The 0.25 metre diameter earthenware pipes laid 1.8 metre below the surface in line with the main walkway which fills the main pools of the complex.
Some of the earthenware pipes were replaced in 1903 with cast iron. The fountain pipes were not connected directly to the fountain heads, instead a copper pot was provided under each fountain head: water filled the pots ensuring an equal pressure to each fountain. Part of the present water supply still uses the tanks of the old aqueduct, which are filled from wells by electric pumps. The arches of the wider arm of the aqueduct that runs west-east have been filled in to house offices for the Horticultural Department of the Archaeological Survey of India, which also uses the area west of the aqueduct extending into the garden of Khan Alam as a nursery.