Nila Gumbad translates to "Blue Dome," and the Nila Gumbad next to Humayun's Garden Tomb is an octagonal tomb with a blue dome. It is located just outside of the southeastern quadrant of Humayun's Garden Tomb. The wall between the Nila Gumbad's site and Humayun's Garden Tomb contains an entrance, leading some to call the wall "The Nila Gumbad Gate." In his book, Humayun's Tomb and Adjacent Buildings, S.A.A. Naqvi says this about the Nila Gumbad in relation to Humayun's Garden Tomb's enclosure wall.
[On the] eastern enclosure wall of Humayun's Tomb, immediately opposite the Nila Gumbad, contains recessed arches which contrast with the plain construction of the wall everywhere else on this side; it also contains a doorway leading to the Nila Gumbad. These features are original and indicate that the Gumbad already existed before, or was simultaneously designed with the enclosure wall.1
The Nila Gumbad Wall has since been reconstructed by the partnership of the Aga Khan Development Network and the Nizamuddin Urban Renewal Initiative.
1. S.A.A. Naqvi, Humayun's Tomb and Adjacent Buildings (Calcutta: Government of India Press, 1947), 14.