Akila Apart City 
Paris has had six successive walls. Of the oldest nothing survives, and of the last one what survives is the ring road. But of Philippe Auguste's, built around 1200, substantial pieces remain, and several are in the Latin Quarter.
A king leaving, and a city with no wall
In 1190 Philippe Auguste was about to leave on crusade. Paris was then an open city on the Right Bank, and an undefended capital worried him. Before embarking he ordered a wall.
The Right Bank works came first, then the Left Bank, finished around 1215. In all, some five kilometres of wall, eight to ten metres high, three metres thick at the base, flanked by more than seventy round towers about sixty metres apart, and pierced by a dozen gates.
Funding was shared: the king paid for the Right Bank, while burghers and religious houses contributed on the Left. For its time it was an exceptional undertaking, and a political act: by enclosing the city, the king defined it.
Where it ran
On the Left Bank the wall left the Seine in the west, near today's Institut de France, climbed south by rue Mazarine and rue de l'Ancienne-Comédie, reached its high point around place de la Contrescarpe, then dropped back to the Seine by rue du Cardinal-Lemoine and rue des Fossés-Saint-Bernard.
The street names still say so. Wherever you read rue des Fossés-Saint-…, you are walking on the outer ditch of the wall, filled in and built over. The word contrescarpe means the outer face of that ditch, which is where the square gets its name.
The Sorbonne is inside. The bourg Saint-Médard and the lower rue Mouffetard are outside, beyond the wall, which explains their long rural poverty.
Where to see it
The fragments are numerous but discreet, often in private courtyards. Four are accessible or visible from the street.
- Rue Clovis, in the 5th. The easiest and most striking in the Latin Quarter: several metres high and some fifteen long, wedged between two buildings, straight onto the pavement. You can touch it.
- Rue des Jardins-Saint-Paul, in the 4th. The longest surviving stretch, about sixty metres with two towers, edging a sports ground. The best place to grasp the scale.
- Rue du Cardinal-Lemoine and rue Clovis, where the line can be read in the alignment and the level of the plots.
- The Louvre. The foundations of Philippe Auguste's Louvre tower, the corner fortress of the wall, are visible in the museum basement. The most monumental piece of all.
Other sections survive in cellars, underground car parks and courtyards in the Marais and the 5th. Some are shown on heritage days.
What became of it
Paris outgrew it quickly. By the fourteenth century Charles V had built a wider wall on the Right Bank; the Left Bank kept Philippe Auguste's for four more centuries, until the eighteenth-century Farmers-General wall.
A wall that is no longer needed is not demolished, it is absorbed. People lean on it, cut windows into it, build on top of it. That is why so much survives: each time a section served as a party wall for a house, it was kept out of thrift.
The street plan keeps the trace more reliably than the stone. Follow the curve of rue Mazarine, rue Monsieur-le-Prince, rue Malebranche, rue Blainville, rue du Cardinal-Lemoine: you draw an arc with no topographic reason. That is the wall.
Frequently asked questions
Where can you see the wall of Philippe Auguste in Paris?
The two most accessible places are rue Clovis in the 5th, where a section stands on the pavement, and rue des Jardins-Saint-Paul in the 4th, which keeps about sixty metres of wall and two towers.
When was it built?
From 1190 on the Right Bank and until about 1215 on the Left Bank, on the orders of Philippe Auguste before he left on crusade.
Why are so many streets called 'rue des Fossés'?
Because they follow the outer ditch of the wall, filled in and built over. The name outlived the ditch.
What does contrescarpe mean?
The outer face of a fortification ditch, the side opposite the rampart. Place de la Contrescarpe owes its name to its position relative to the wall.