Tower D is on the western side of the bastion of Su Nuraxi (15th-13th century B.C.), in a side position (figs. 1, 2).
The perimeter tower (fig. 3), that can be accessed from the courtyard through an architraved entrance and a corridor that is 3.88/2.90 metres long and 1.00/1.99 metres wide, that was originally formed by two chambers one over the other. The base diameter and the vault height are 4.00 x 7.73 metres. The tholos vault is no longer complete.
The double row of embrasures (nine on the lower level and eight on the upper level) made in the wall of the lower chamber, can still be seen, as they were not hidden inside, but only on the outside. In the space between the entrances to towers D and E, there is an entrance (1.67 metres high) at 3.65 metres from the ground leading into a small subsidiary tholos chamber (4.23 metres diameter by 5.20 metres height), with a niche and jamb in the wall, that can be reached from the courtyard using a mobile ladder.
- LILLIU G., Il nuraghe di Barumini e la stratigrafia nuragica, in Studi Sardi, XII-XIII (1952-1954), Sassari 1955.
- LILLIU G., I nuraghi. Torri preistoriche della Sardegna, Verona 1962, pp. 181-191.
LILLIU G., ZUCCA R., Su Nuraxi di Barumini, Sardegna archeologica, Guide e Itinerari, Sassari 1988.
- MURRU G., Barumini. Su Nuraxi e il villaggio nuragico, Fondazione Barumini Sistema Cultura, 2007.
- SANTONI V., Il nuraghe Su Nuraxi di Barumini, Guide e Studi, Quartu Sant’Elena 2001.
- USAI L., Il nuraghe Su Nuraxi, Barumini, in CAMPUS F., LEONELLI V. (a cura di), Simbolo di un simbolo: i modelli di nuraghe, Monteriggioni 2013, pp. 324-329.