This mosque was built by the founder of the Hafsid dynasty after declaring independence from the Almohad authority in Marrakech.  The prayer hall is The prayer hall is deeper than it is wide, and divided into seven naves and seven bays.  It was renovated in 1584/922 AH by the Ottomans, at which time the wooden minbar was replaced by a stone minbar covered in marble.  According to the authors of Qantara, the most impressive and architecturally influential component of the mosque is the minaret,   

whose decoration reproduces the main features of Moroccan and Andalusian Almohad minarets, though it is executed in stone and not in brick, as in Moroccan prototypes. Interlocking multifoil arches cover the square tower from the base upward, creating a delicate network of ochre-coloured diamonds. The upper portion of the minaret is pierced on each side with a triple horseshoe arch framed by a strip of ceramic facing. The tower is capped by a square lantern decorated on each side with a flat niche in the form of a horseshoe arch. [1]

NOTES: 

1. "Grande Mosquée De La Qasaba." Qantara -. Accessed October 27, 2014. http://www.qantara-med.org/qantara4/public/show_document.php?do_id=409.

SOURCES: 

"Grande Mosquée De La Qasaba." Qantara -. Accessed October 27, 2014. http://www.qantara-med.org/qantara4/public/show_document.php?do_id=409.

"Kasbah Mosque - Lonely Planet." Lonely Planet. Accessed October 27, 2014. http://www.lonelyplanet.com/tunisia/tunis/sights/architecture/kasbah-mosque.