The Baba-Vali Mosque is located in the historic center of Kashan, to the north-west of the city's central square. The date of the mosque's foundation is unclear, but inscriptions dating its tilework to 1859-1860/1276 provide a terminus ante quem.
The main entrance of the building is through an ornate portal off a covered bazaar street. The portal's domed vestibule takes the form of a rectangle with angled corners (hasht-u-nim-hasht). A corridor on one of its side walls leads onto the main courtyard, whose axis is oriented toward the qibla and skewed from that of the street and vestibule by an angle of approximately forty-five degrees. The corridor turns at an angle to accommodate this change. The courtyard is rectangular with a cross-shaped fountain at its center.
On its southeastern side, a large iwan opens onto the court. The back of this iwan is an apse in the form of a half-octagon. A screened window pierced through one of its angled corners looks onto the entrance vestibule behind it. Flanking the southeastern iwan on its right is the muqarnas-vaulted mouth of the bent entrance corridor described above, and to the left is a small covered porch that gives access to a stairwell leading to the upper story of the facade, which features rooms with balconies overlooking the courtyard. Tucked out of view, a door in the corner of this porch leads onto a long and irregular corridor that eventually reaches a second courtyard surrounded on two sides with rooms.
The southwestern (qibla) side of the courtyard features a great iwan, taller than the southeastern one but similarly decorated, flanked by two smaller archways. These apertures lead onto three vaulted bays of a prayer hall. The central bay, behind the large, central iwan, is the grandest and tallest, and terminates in a half-octagonal apse.
Moving clockwise around the court from the qibla iwan, the northwestern side is occupied by a large platform nearly as large as the courtyard itself, access to which is provided by a staircase on its northeastern side. This platform is flanked on its two lateral sides by single story facades and on its rear (northwestern) side by a single story facade with a central iwan and two blind arches on either side. A staircase on the southwestern wall of this platform leads up half a story to a hypostyle prayer hall hidden behind the facade.
The platform covers a sardab-level hypostyle prayer hall, which is accessed through a staircase on the northeastern wall of the lower courtyard. This sardab prayer hall is three aisles wide, each seven bays long. The bays on the southeastern wall of the prayer hall have windows near their tops overlooking the courtyard.
No large iwans open on the opposite side of the lower courtyard from the qibla (northeastern). Rather, several shallow niches of irregular width and depth line the wall. The niche to the furthest left houses a stairwell that descends to the sardab prayer hall.
Ḥājjī-Qāsimī, Kāmbīz, ed. Ganjnāmah-i farhang-i ās̲ār-i miʻmārī-i Islāmī-i Īrān, Vol. 6, 160-165 (English text: 128-133). 18 vols. Tehran: Dānishgāh-i Shahīd Bihishtī, 1996.
Nārāqī, Ḥasan. Āsār-i tārikhī-i shahristānhā-yi Kāshān va Naṭanz, 264. [Tehran: Anjumān-i āsār-i millī, 1348/1969].