The historic monument known as Darb-i Kushk consisted of the remnants of a portal constructed during the Timurid Period in 1496-1497/902 A.H. This portal probably formed the entrance to a zawiyya. By the beginning of the twentieth century, nothing remained of the structure except the portal itself, which spanned a narrow street that had been cut through the neighborhood at some point in the city's history. The portal, as it stood in 1900 when surveyed by Friedrich Sarre, consisted of a monumental arched iwan crowned by a muqarnas-vaulted semi-dome. The vaulted iwan was framed by a pishtaq. The upper half of the iwan was sparsely but elegantly decorated with brickwork and diamond-shaped medallions containing square Kufic calligraphy, while its lower half was covered by tile mosaic dadoes of geometric repeat patterns surmounted by an inscription band. The inscription named the patron and date of construction.
The Darb-i Kushk was in bad condition, its decorations and semi-dome having deteriorated over the centuries. In an effort to preserve the ornamentation, the tile revetments were removed from the in-situ portal and re-mounted on a model of the portal constructed in the gardens of the Chihil Sutun Museum in Isfahan. Comparison between photographs of the in situ portal in the early twentieth century and the reconstructed model show that the model appears nearly but not perfectly true to the original form of the monument.
Golombek, Lisa and Donald Wilber. The Timurid Architecture of Iran and Turan. Princeton: Princeton University Press, 1988. Cat. No. 173 (p. 389).