Gol Gumbaj, literally means the round dome, is the tomb of Mohammed Adil Shah (1627-56 AD), the 7th ruler of this dynasty. It was built at his orders before his death by the renowned architect Yaqut of Dabul. It was the desire of the ruler to build a mausoleum comparable to the Ibrahim Rauza, the tomb of his father, Ibrahim Adil Shah II. The Ibrahim Rauza was an exceptional tomb in composition and ornamentation. Gol Gumbaj is one of the biggest single chamber structures in the world. It was build over a floor area of 1700 sq m with a height of 51 m and diameter of 37 m. the walls of the tomb are 3m thick. The central dome of Gol Gumbaj does not rest on any pillar and is second to the dome of St Peters Basilica, Rome in size. The unique feature of the tomb is its acoustic quality. A sound echoes 11 times over and can be heard at a distance 37 km.
The mausoleum is part of a bigger complex that includes a mosque, a dharamshala (inn) and other buildings. The work of the mausoleum was never properly accomplished as was thought since construction began towards the end of Muhammad Adil Shah's reign. As a result, the tomb is a plain square block with towers on each corner. The tomb is built of dark gray basalt and decorated plasterwork. The walls are 3 m thick and 30.5 m in height. The measurement from the interior is 41m on each side. Each exterior face of the structure displays three great blind arches. The central arch is wider than the others and is dressed with wooden panels with small rectangular entrance and three rows of arched windows punched through.
The south door is the main entrance to the tomb. A bijli patthar (meteorite) is suspended by a chain from the cornice. It is said to have fallen during Muhammad Adil's reign and is believed to guard the tomb from lighting. The cornice and parapet of the building is the most distinct characteristic of the fašade. The cornice rests on highly carved stone corbels that project to about 3 m from the wall. The cornice supports the parapet, which has a row of arched openings and leaf-shaped walls.
The mausoleum is topped by a monumental dome. The base of the dome is carved with elegant petals that cover the drum. The diameter of the dome from outside is almost 44 m and attains the height of 27.4 m from a circular platform. The total height of the dome from ground level up to the top from outside is 60 m. The dome rests on the system of pendantive, which is a system of intersecting arches. It was not used anywhere else in India. The only other example of this kind was the Great Mosque of Cordoba. The eight high pointed arches bisect in the interior of the cube at regular intervals. The high circular platform with an opening of 29.5 m in diameter rests on their point. The interior of the dome converges with the edge of the circle by about 4 m so that part of the weight falls on the intersecting arches that bear and neutralize any other exterior forces. The dome is built of horizontal rows of brick with a flat section at its crest. It is cemented with lime and acquires a thickness of 3.5 m. There are six openings at its base.
The corner towers are inharmonious with the rest of the mausoleum. They are divided into seven floors with a projecting cornice and a row of arched openings marking each level. The towers give the look of Chinese pagoda rather than the minarets. Each tower is crowned by a hemispheric dome with a ring of carved leaves around its base.
The cenotaphs of the Mohammad Adil, his two wives, his mistress Rambha, his daughter and grandson are in the center of the tomb. The primary cenotaph is made of wooden canopy. The real graves are in the basement, which can be accessed by a staircase below the entrance on the west.
A very strong circular foundation was discovered in the basement that resembled the circular opening of the dome above. But this foundation supports only a platform and a light wooden pavilion. This could be explained that the original plan may have been based on the conventional mausoleum plan of a small domed chamber surrounded by an open colonnade. It was after the completion of the foundation work that the king or architect thought of resting the dome upon the outer walls, thereby enlarging the volume of dome several times.
The gallery around the base of the dome of the mausoleum possesses an interesting feature that it hangs out about 3.54 m. and is accessed through the winding staircase in the four towers. It is known as the whispering gallery because the sound reflections from the dome allow the slightest of whisper to be heard even when standing across the dome from each other.
This mausoleum is one of the Bijapur's main architectural treasures. Despite its incomplete condition, the absolute stateliness of the structure makes visitors awestruck. The architecture of the building provides an exoticism that blends with monumentality and prevents this building from becoming just another building imitating the classic Mughal architecture.