Al-Bakri, an Andalusian author of the mid-11th century, to whom we owe a detailed description of the medina of Tunis and its surroundings, is the first to have revealed to us the names and the locations of the five gates through which the city of the early Middle Ages communicated with the outside world. Among these openings four are well known to us: Bāb al-Saqqā’īn (later Bāb Suwayqa) in the North, Bāb al-Ğazīra in the South, Bāb al-Baḥr and Bāb Qarṭāğanna in the East. Only the door opening to the west by the name of Bāb Arṭa has remained enigmatic as to its exact location on the western rampart as well as its attribution to Arṭa. What was Arṭa supposed to be? Was it a location the west side of the city which would have given its name to the gate after the example of Carthage (Bāb Qarṭāğanna) or Cape Bon, Ğazīrat Sharīk (Bāb al-Ğazīra)? These are the questions that the article attempts to answer by drawing on various types of documents: historical, geographical, topographical, toponymic, and cartographic sources. After probing a number of toponyms which corresponded more or less to the pre-established criteria, two sites were selected: the first Uthina (the current Oudhna) located 22km from the capital on the road to Zaghouan, the second Ṭunbuḍa (the current Muḥammdiya), and located 15 km in the western suburbs of Tunis. Far from deciding clearly in favor of one or the other possibility, the author concludes with a hypothesis which remains to be checked: Would Ṭunbuḍa rather be the Arṭa mentioned by Al-Bakri, and whose name would have accordingly been attributed to the door in the western part of Tunis. The latter, which we have never heard of since the 11th century, would have disappeared in the turmoil of the Hilalian invasion or, at the latest, following the conquest of Tunis by the Almohad caliph Abdelmoumen and the construction of the Kasbah in 555/1160.