It must be remembered tomb structure was not popular in early Islam. The earliest known such square structure is the tomb of Ismail, the Samanid at Bukhara, the original model being perhaps the Chahartaq, the four Doored Sassanian fire-temple of Iran.
History goes that one lakh rupees was spent in its construction and hence the name Eklakhi Mausoleum was given. The date remains unknown, but generally is taken as the death year of Jalaluddin Muhammad Shah. Jalaluddin Muhammad Shah died in the year 1433 AD.
Eklakhi Mausoleum is situated to the southwest of Adina Mosque. Adina Mosque was built in 1373 by Sultan Sikandar Shah, the Second Sultan of the Ilyas Dynasty. Eklakhi Mausoleum is made up of brick, and stands at a little distance to the northeast of the Qutb Shahi Mosque which was built in honour of the saint Nur Qutb Alam.
The exterior of the building is strengthened by four octagonal towers at the corners, and is opened by four doorways, one each in the middle of each side. Pointed arches with lintels crowning the doorjambs span the doorways, a feature derived from the original Hindu temples through architectural style of Tuglaq Dynasty. The jambs and the lintels are marked by carved Hindu deities - that of the lintel of the southern entrance being the figure of Lord Vishnu, and of the jambs those of Dvarpals, a proof of their appropriation from Hindu temples. Inside the Eklakhi Masjid, there are the remains of three sarcophaguses. The western one seems to be the tomb of the Sultan, the middle one that of his wife, and the eastern one that of his son Sultan Ahmad Shah. A peculiar feature of the inner spacious room is its four alcoves built at the corners, often taken as cells for readers of the Holy Quran.
The ornamentation of the Eklakhi Masjid or mosque consists of braced string-mouldings of the corner towers, a divider moulding of the whole external appearance, and the cornice mouldings in three tiers beside the terracotta plaques in panels underneath - now broken - imitated from the designs of the Adina Mosque. The interior of the dome was once ornamented with plaster but is now dilapidated condition. The dome of this mosque, like all other domes of the Sultanate Bengal, appears to be covered with a round rim in the form of a Hormica, a Buddhist feature. The hemispherical dome is in fact very much in the shape of the domes of the great Stupas.
This entailed making the cornice carve downward from the middle to the sides in imitation of the sloping roof of Bengali huts. Once established this practice continued throughout the period of Sultanate architecture in Bengal, not only in single domed structures, but also in multi-domed large mosques. It also set the example of single domed structures in Bengal, not only in Sultanate building art, but also in Mughal architectural style. Its great contributions to the development of the Bengal style could be seen fully in the later half of the 15th and early 16th centuries.