Paris rediscovers its first medieval fortifications

Visible for about 20 metres, this V-shaped dry ditch is approximately 12 metres wide and 3 metres deep. Being the only fortification in the capital with no preserved built remains, it is the most poorly documented. Consequently it has sometimes been called the "Carolingian wall" and at other times the "11^th century wall". It is the second city wall of Paris, situated between that built in Late Antiquity (early 4^th century, on the Ile de la Cité) and that of Philip Augustus (around 1200, built on both banks). From the 10^th century onwards, after the Viking  invasions and particularly during the siege of Paris from 885-886, the right bank experienced significant economic and urban development and its protection thus became a necessity.

After its destruction, this fortification was simply forgotten. During the 18^th century, historians suspected its existence and attempted to identify its plan through toponymical indications: porte Baudoyer, archet Saint Merri, etc. Different plans were proposed based on the study of land boundaries. Today researchers agree that the wall surrounded the church of Saint-Gervais to the east, the churches of Saint-Merri and Sainte-Opportune (which no longer exists) to the north, after which it followed the rue de la Ferronnerie and ended at the church of Saint-Germain-l'Auxerrois. This last section was the most disputed, with some authors proposing shorter fortifications ending at Châtelet and leaving Saint-Germain-l'Auxerrois unprotected. The discovery of the ditch at the rue de Rivoli confirms the position of the eastern section.

The age of this defensive construction and its political context remain to be clarified. The hypothesis that it was attacked by the great Viking army during the siege of 885-886 is no longer tenable. The first elements dating it to the 10^th-11^th centuries were found in 1995 during an excavation by Afan at 15 rue du Temple. The pottery found at the  rue de Rivoli will help to better date the fortifications.
Should they, for example, be attributed to Eudes, Count of Paris during the siege, who was later King from 888 to 893, or his brother Robert, even more briefly King from 922-923, or perhaps to Hugues Capet at the end of the 10^th century? The 10^th century was indeed a period of transition during which the power of the Carolingians weakened while that of the Robertians (Counts of Paris and ancestors of the Capetians) increased.