The tomb of Jahan Begam is unfinished but is similar and size and design to the
Gol Gumbaz, with four corner towers and a square plan surrounded by a double arcade with three arches on each face between the corner towers. The four central facade arches are left open, unlike Gol Gumbaz. Inner walls were intended to enclose the tomb chamber and support a dome. It is uncertain whose tomb this is, as two wives of Muhammad Shah lie next to him in the Gol Gumbaz, so this may have been a third wife, or his mother.
Sources:
Merklinger, Elizabeth Schotten. Indian Islamic architecture: the Deccan 1347-1686, 127. Warminster, England: Aris & Phillips, 1981.
Merklinger, Elizabeth Schotten. Sultanate architecture of pre-Mughal India, 145. New Delhi: Munshiram Manoharlal Publishers, 2005.
Michell, George, and Philip Davies. The Penguin guide to the monuments of India. Vol. 2, 438. London, England: Viking, 1989.