The Great Mosque of Hamadan is located in its historic bazaar. An inscription in the southern iwan of the building dates its construction to 1838/1253 AH. 

The mosque occupies an irregular plot of land and its borders bleed into the surrounding urban fabric. The interior of the mosque is arranged around a large central courtyard and three large iwans. It is built on two levels: while the main entrances are at street level, the central courtyard and its adjoining structures sit below street level so that patrons must descend to reach them.

The mosque's main, monumental entrance is through an ornate iwan-shaped portal on Khiyaban-i Ikbatan, one of the arterial streets radiating from Hamadan's central town square that passes the east side of the mosque. This portal is a recent addition to the mosque, and conforms to the orientation of the newer street while the courtyard and its adjoining buildings conform to a roughly northeast-southwest axis in accordance to the qibla. At the back of this entrance iwan are two doors. The right-hand door leads onto an octagonal vestibule from which patrons can descend a flight of stairs leading onto an archway at the north end of the eastern facade of the mosque's central courtyard. The octagonal vestibule also gives access to upper floor rooms overlooking the courtyard on its east side. The mosque has another entrance on its west side, which leads down several stairs onto an open corridor and through a domed vestibule leading onto the west facade of the central courtyard.

The mosque's central courtyard is rectangular and has a central rectangular pool as well as a rectangular garden plot and a smaller octagonal pool toward its east end. The qibla (south) iwan is the largest and is adorned with brickwork. It gives onto a domed chamber flanked on both sides by shabestans (covered prayer halls) consisting of several vaulted chambers supported by large piers. The iwan directly opposite the qibla (on the north side of the court) is also ornately decorated, in this instance with tile revetment. It gives onto a hypostyle shabestan occupying the northern end of the building. On the east side of the courtyard, an iwan opens onto a domed chamber and is flanked by two narrow halls. On the west side of the courtyard, the iwan is replaced by the aforementioned domed vestibule giving access to the corridor leading to the entrance on the side of the building. On either side of this vestibule and entrance corridor are two hypostyle shabestans: one rectangular hall that occupies the southwestern corner of the building consisting of nine rows of five vaulted bays, and one irregularly shaped hall occupying the northwestern corner of the building consisting of four rows of three bays and two rows of two bays.

The mosque has six minarets: two on the qibla iwan, two on the iwan opposite it, and two rising above the northeastern entrance iwan.