The Bab al-Khamis — 'Thursday gate', so called because the weekly market was held outside it — is the best preserved of the old gates of Tlemcen, marking the south-west corner of the medieval walls. It is a rusticated horseshoe-arched gateway flanked by two short bastions, built into the surviving fragment of Almohad-era city wall.
The gate itself is open in passage — you can walk through it as locals do on their way to the modern souk that still operates beyond. From the outside, looking back at the medina from the gate, you get the best sense of the urban texture of old Tlemcen: tightly packed pale houses crowned by the slim minarets of the Great Mosque and Sidi Belahcen.