The Bara Imambara complex was designed by Kifayatullah Shahjahanabadi of Delhi and is said to have cost one and a half crore of rupees. It is also said that 22,000 workers were engaged, day and night, for its construction. It is located on the Southern and western slopes of the mound over which there once stood the famous Machhi Bhavan Fort. It runs in an east-west direction, with layered subterranean chambers in the south.
It can be approached by means of two lofty gateways. The one lying to the South is the entrance while the other one, to the north, was constructed for reasons of symmetry. It housed the Naubat Khana or music gallery. It has projecting balconies on its tri-arched facade. The entrance gateway is remarkable for its rectangular plan, its tri-arched facade similar to the tripolia of Mughal gateways, its bold cusped arches and its double sets of fish in thick lime plaster, facing each other on the spandrels. The raised parapets are composed of miniature domed arches, with square turrets at the corner. These turrets are crowned by Chhatris or cupolas. In between are miniature turrets crowned by Guldastas. The side walls have arched galleries on both sides with a series of fluted domes, flanked by octagonal bastions at the corners. These bastions are crowned by domed Chhatris. Inside the southern gateway is a spacious forecourt at the end of which is another imposing tri-arched gateway leading into the main courtyard. The Imambara is towards the south and the mosque to the west. Built on a raised platform and approached by flights of steps, the Imambara is magnificent in its size, architectural setting and symmetrical proportions.
The main building of the Bara Imambara is an impressive, massive single-storied monument. It is approached by a flight of stone steps and the facade of this large edifice has multi-tiered parapets with miniature-domed cupolas on both sides. The contour is also broken by slender turrets, crowned with Guldastas, at the corners. Another interesting feature is the side wings with arcuate galleries.
The rear part of the Imambara consists of the Shahnashin, which has thirteen arched openings. It is embellished with costly tazias and alams. The central hall is 49.68 meters long and 16.15 meters high. The most outstanding feature of the central hall is that it is vaulted without the support of pillars or pilasters, or even the use of iron or wood. It is one of the largest halls of its kind in the world and is rightly considered to be one of the great architectural achievements of India.
Octagonal Shahnachis, about 16.15 metres high with walls measuring 4.87 meters in thickness, flank the Shahnashins and halls. The ceilings are beautifully decorated with painted motifs below, which are small projecting balconies, a popular feature in Mughal palace architecture. In the centre of the hall is the tomb of Nawab Asaf Ud Daulah and next to it is the grave of his wife Shamsun Nisa Begum. Both the halls are tastefully decorated with beautiful and costly chandeliers, most of which were manufactured in Belgium and England. Besides, there are several large mirrors with gilded wooden frames. Only a few such precious antiquities remain but before the struggle of 1857, such decorative objects were in great number. During the seventh, eighth and ninth days of Muharram, these chandeliers are lit, and the effect is dazzling.
Along the southern part of the Imambara lie 489 identical openings from the first to the third storey. These openings were created at regular intervals for air and light, and one has to ascend and descend steps at different levels. A Bhool Bhulaiyya or labyrinth has been created due to this complicated arrangement of identical openings through the thickness of the walls.
The architectural style of the mosque follows the conventional plan of the later Mughal mosques. There can however be seen a definite sense of space in the wide facade and elevated basement of the mosque. The double halls measure 55.77 meters in length and have a combined breadth of 24.68 meters. The arched ceiling rises to a height of 9.75 meters. The ceilings are rather tastefully decorated and the Mihrabs in the western walls are conspicuous for their arabesque designs.
Baolis or step-wells are a definite class of buildings in Indian architecture, and are more elaborately constructed in western India, particularly in Rajasthan and Gujarat, where there is paucity of drinking water. These Baolis are multi-storeyed and have cells at each level for the comfort of the users.
The Shahi Baoli is situated in the eastern side of the Asafi Imambara complex. It follows the conventional architectural plan and has a deep circular well at the eastern end. It is approached through a flight of steps and a door facing west. The multi-storeyed Baoli, which has open galleries and cells at each level, is built on a rectangular plan with Lakhauri bricks and lime mortar. It has spacious cells, notable for their arcuate ceilings. Some of the cells in the lower storeys are always under water.
Another great architectural achievement of Nawab Asaf Ud Daulah is the Rumi Darwaza. It was built in 1784 and is an important landmark of the historic city of Lucknow. This lofty archway consists of an 18.28-meter high portal surmounted by an elaborate cupola and flanked by low curtain walls pierced by cusped windows with octagonal bastions at the sides. It is believed that the architects of the Rumi Darwaza attempted to improve upon the historic gateway of Constantinople (now Istanbul), which is why the gateway was thus named. However this does not seem to be an actual fact as the architectural features of the Rumi Darwaza do not bear any foreign impression. In fact the Mughals were master builders of gateways, surpassing the kinds found in Central Asia and Iran during the middle ages.
The architect of the Rumi Darwaza designed a unique, massive gateway with recessed arches, both plain and cusped, in Lakhauri brick and thick lime plaster with floral motifs crowning the apex of the inner arch. The outer arch has bold and broad lotus petals alternated by solid turrets with floral patterns. The Mughal element is noticeable in the minarets, crowned by octagonal Chhatris.
The apex of the outer arch is crowned by an octagonal domed booth, which has added considerable symmetry and grandeur to the form. On the western side, the gateway has three arched openings. The arcuate ceiling is decorated with floral motifs. The kiosk of the Rumi Darwaza provides a panoramic view of Lucknow city and in particular, of the unique architectural setting of the Asafi Imambara complex.
The Asafi Imambara is one of the most outstanding architectural constructions of Lucknow. It continues to be a prime tourist attraction and forms an important landmark of the historic city.