The Mausoleum of Baba Rukn al-Din (Persian: مقبره بابا رکن الدین) or just Mausoleum of Baba Rokneddin is a mausoleum located within the grounds of the Takht-e Foulad cemetery in Isfahan, Iran. It is number 201 on the list of national monuments of Iran. The mausoleum entombs the remains of the Sufi mystic Masoud ibn Abdullah al-Beyzawi, who is known by his title Baba Rukn al-Din.

The original construction of the mausoleum dates back to the Ilkhanate period. During the reign of Shah Abbas I, restorations and renovations were done to the mausoleum. These works added a tiled porch and several new facilities to the mausoleum. Baba Rukn al-Din's tomb was the only surviving structure from the Ilkhanid era, and this remains true in the present time.

The mausoleum is made with bricks, while the exterior of the building is covered in decorative tiles. The dome is conical in shape, but has five sides.

Inside the mausoleum, there are alcoves on each side of the structure (save for the entrance). One of them holds the grave of Baba Rukn al-Din. His grave has a tombstone made of marble.

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  An illustration of the mausoleum by Pascal Coste from 1840
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  A close up of the mausoleum's exterior
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  A signboard outside of the mausoleum
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  The grave of Baba Rukn al-Din inside the mausoleum

• Baba Rukn al-Din
• List of mausoleums in Iran