Molla Hassan ibn Mohammad Kashani, known as Hassan Kashi, was a poet from the Ilkhanate period, most of whose poems were about praise of the Prophet's family. His tomb is currently located about two kilometers south of Gonbad-e Sultanieh. An interesting feature of this building is its triple-shell dome. This means that the dome of Molla Hassan Kashi includes three inner walls. The design of Molla Hassan Kashi's tomb follows the pattern of Safavid-era tomb construction, meaning that the building has an octagonal plan that turns into a cross-like space in the interior. One of the prominent features of this building is the use of Bannai script made of turquoise brick and tile on the neck of the dome and also on the exterior facade. The interior surfaces of the dome are decorated with suspended stucco decorations in white and brown. The exterior view of this shrine has an octagonal plan which has been transformed into a square shape through combining and merging side iwans in the interior. The four iwans on the ground floor are connected to each other by a beautiful hallway. The small iwans, each including two stories, are connected to the large iwans on the ground floor via a staircase. The result of this connection is a beautiful dome that sits on the core of the central four-sided structure. This dome, with a relatively tall stem, is of the type of double-shell domes with an additional decorative layer. The stem of the dome is divided into four sections in terms of decorations: the first section features an inverted palm motif, the second section includes divine names and phrases such as" Allahumma Salli Ala Muhammad Wa'ala Ali Muhammad" in Bannai Kufic script, the third one showcases zigzag decorations, and finally, the fourth part is adorned with parallel lines of turquoise brick combined with tile decorations.