Wall of Philip II Augustus

The Wall of Philip Augustus is the oldest city wall of Paris (France) whose plan is accurately known. Partially integrated into buildings, more traces of it remain than of the later fortifications which were destroyed and replaced by the Grands Boulevards.

The wall was built during the struggles between Philip II of France (called Philip Augustus) and the Anglo-Norman House of Plantagenet. The French king, before leaving for the Third Crusade, ordered a stone wall to be built to protect the French capital in his absence.

The Right Bank was fortified from 1190 to 1209 and the Left Bank from 1200 to 1215. The difference in completion dates was probably strategic. The Duchy of Normandy was in the hands of the English Plantagenet dynasty so an attack would most likely come from the northwest. Philip Augustus decided to build the fortress of the Louvre to strengthen the defence of the city from attack from the Seine. The Left Bank was less urbanized and less threatened and thus considered less of a priority.

Despite the construction during the 14th century of Charles V's wall encircling Philip Augustus' wall on the Right Bank, the latter wall was not demolished. In 1434, it was still considered strong enough and thick enough for a cart to be driven on top.

However, Charles V's wall did not extend to the Left Bank, so the Philip Augustus' old wall was strengthened by:

In 1533, Francis I demolished the Right Bank gates and authorised the leasing of the land enclosed by the wall without authorising the demolition of the wall itself. From the second half of the 16th century, these lands were sold to individuals, and often the cause of the dismantling of large sections of the wall.

The Left Bank wall followed the same path under Henry IV. In 1590, he preferred digging ditches beyond the city outskirts to once again modernising the wall. The ditches near the Seine were used as open sewers and caused health problems so in the 17th century they were filled and replaced by covered galleries. The last remaining gates, unsuited to ever-increasing traffic, were rased in the 1680s from when the wall became completely invisible.

...
Wikipedia