Shah Nizar's Mausoleum is a group of tombs marking the graves of the Shah Nizar (d. 1722/1134 AH), the fortieth imam of the Qasimshahi Nizari Isma'ilis, and other members of his family. He and his family are ancestors of the Aga Khan. Inscriptions ranging from 1699/1111 AH to the end of the 18th/12th century AH date the original structure to circa 1700/1111 AH. Renovations in 1966 significantly altered the tomb's appearance.
The tomb is located in what was once probably the home of Shah Nizar. It lies at the edge of the village of Kahak along the base of the hill overlooking the village from the west. Just to the north stands a large Safavid caravanserai that speaks to the town's importance as a way station during that period.
The structure is a rectangular block surrounded on three sides by a walled garden sloping down to a stream. It contains several chambers, each with a number of tombs. These chambers are open onto the garden through arched portals. Inscriptions in Sindhi characters demonstrate that pilgrims came to Kahak all the way from India to visit the site. In a description written in 1938, the mausoleum featured a carved wooden door and wooden screens, which have since disappeared. The building was restored in 1966.