The Skifa Kahla (Arabic: السقيفة الكحلة), also known as Bab Zouila,[1] is a fortification of the 10th century, the structure is one of the few remnants of the ancient walls of Mahdia in Tunisia.

[3] The fort is one of the few remnants of the ancient ramparts, as well as being one of the access points to the historic center of Mahdia.

[8] The building served as a defense to prevent Christian invasions as well as imperial wars to the city of Mahdia.

[15] The building renovations were conducted by the Tunisian National Heritage Institute to commemorate the 1200th anniversary of the founding of the city of Mahdia.

[17] The structure of the fort comprises a vaulted passage which is divided into sections by gate-loops in addition to a portcullis.