“In AH 631 he invaded Malwah, and after suppressing the rebels of that place, he destroyed that idol-temple which had existed there for the past thre… - Iltutmish

From thence he advanced to Ujjain-Nagari and destroyed the idol-temple of Mahakal Diw. The effigy of Bikramjit who was sovereign of Ujjain-Nagari, and from whose reign to the present time one thousand, three hundred, and sixteen years have elapsed, and from whose reign they date the Hindui era, together with other effigies besides his, which were formed of molten brass, together with the stone (idol) of Mahakal were carried away to Delhi, the capital.

After the reduction of Gualiar, the King marched his army towards Malwa, reduced the fort of Bhilsa, and took the city of Oojein, where he destroyed a magnificent temple dedicated to Mahakaly, formed upon the same plan with that of Somnat. This temple is said to have occupied three hundred years in building, and was surrounded by a wall one hundred cubits in height. The image of Vikramaditya, who had been formerly prince of this country, and so renowned, that the Hindoos have taken an era from his death, as also the image of Mahakaly, both of stone, with many other figures of brass, were found in the temple. These images the King caused to be conveyed to Dehly, and broken at the door of the great mosque.

Naqvi has taken pains to describe at length the edifice which began as a temple, got converted into a tomb and to which was added a masjid with a marble mehrab and then a gate with pretty Arabic calligraphy of verses from the Holy Quran. As he puts it, the gateway projects 13 ~feet from the enclosure wall and is approached and entered by a flight of steps flanked by two square rooms which are roofed with stone slabs in the Hindu fashion. The external archway of the gate is formed by overlapping courses of marble and around it is the important Arabic inscription in Kufic characters.
He goes on, after crossing the threshold, one stands under the eastern colonnaded verandah, the flat roof of which rests on red sandstone pillars. The latter are not uniformly carved, indicating that they have been re-used here from an older building. Opposite this colonnade and along the whole length of the west em wall runs another colonnaded verandah with a prayer chamber in the centre erected in white marble and covered with a corbelled pyramidal dome. The dome is almost certainly re-used and is lavishly carved internally with Hindu motifs, notably bands of lozenge or triangular patterns. The marble mehrab is embellished with verses from the Quran and a floral design. The floor is paved with marble slabs. The rest of the verandah on either side of the prayer chamber comprises red sandstone pillars and pilasters supporting a flat roof of Hindu design, with a brick work parapet...
He winds up his description with the words: The Hindu elements in the architecture of the monument are apparent in the dome of the mosque and the partly defaced Hindu motifs on some of the pillar brackets of the western colonnade. The presence of a Gauripatta or receptacle of a linga in the pavement of the western colonnade is a further significant point. Furthermore, the marble stones in the external facade of the mosque are serially numbered, indicating their removal from elsewhere.