Paris' Growth over Grottoes

Paris is a town seated upon the very materials from which it was built. Stone, clay and plaster are all minerals found in the Parisian basin, and only the latter came from regions to its outskirts. Land far from a city centre tends to be treated much differently than land one intends to build upon, but in the “present” of any given point in time in a city’s history, one exploiting suburban terrain gave little thought to what its future would be. This, for Paris, was a recipe for danger.

Before getting to the actual growth of Paris over its formerly empty land, I would like to take a minute to detail a period of its architectural and demographical past that is often but briefly discussed in history books: it Merovingian-era Left Bank. Though it may seem as an “aside”, it is important I think to any discussion of Paris’ mining activity, as it explains why its underground went practically untouched for a period of over five centuries.

Early Mining vs. Town Demographics

The first real mining activity Paris saw was most probably during its Roman occupation. Nineteenth-century excavations uncovered vestiges of truly ancient underground caverns that seem to have been the work, according to their state and the signs of a rudimentary extraction left behind, but may have dated from a later era. In any case, the oldest mines Paris knows were in areas along today's rue Jussieu and below the Jardin des Plantes, to what would have been the southeast suburbs of Lutèce. Gallo-Roman clay mines, mentioned in detail in the previous chapter, have been found closer to what would have been the town centre at a location to the southeast of today's Pantheon. Plaster mining of that time was of little consequence to the city as it was available close to the surface in the southern flank of the hill of Belleville and most probably exploited by open quarry.

Instead of looking (vainly) for evidence of the extent of Paris’ mining activity in the mines themselves, we could take general city demographics into account. As mentioned before, the Roman town of Lutèce at its apogee of growth in 200AD, in addition to group of houses around the Right Bank Cardo and much of the île de la Cité island, covered a plot of land the shape of an inverted kite between the Petit Pont and the rue Saint-Jacques above the Val-de-Grâce hospital. The German invasions into the Roman territory from 235AD seemed to disrupt trade routes and Lutèce's population began to decline. By 400AD the city had few living outside of its fortified city island.

Thus, after a first period of fervent activity, the need for building materials went into decline and mining probably almost stopped altogether. In fact the town went into a period of stone recycling: he abovementioned fortifications was built in its majority (where it could still be found) with stone recuperated from former Left Bank constructions. In fact it is thought that construction continued in this way through the Merovingian dynasty; Paris’ population eventually went back to its former Left Bank and Cité island centres of habitation, but it saw few new major stone constructions during that period. In fact it seems that only churches and palaces were built out of stone then, but next to nothing remains today. We have only texts that, amongst other smaller churches, speak of the ancestor to what would become the Abbey Saint-Germain-des-Prés and a drawing of the round “Saint-Germain-le-Rond” church that was the ancestor to today’s Right Bank Saint-Germain-l’Auxerrois. The Normans destroyed most everything on the Left Bank save the Abbey Saint-Germain-des-Prés in their 9th century raids and again Left Bank stone was recuperated to fortify the island. Thus, from 200 to 900AD, Paris’ mines hardly evolved at all.

Rather than return to its former Left Bank, Paris began to fill the Seine’s northern shore. The first permanent building began around the Grand-Châtelet stronghouse guarding the bridge (today’s place du Châtelet) and the hillock Saint-Gervais just to the east from there. Abbeys and landowners began filling in the marshland surrounding, and new quarters began to appear from the 10th century to the north of Saint-Germain-l’Auxerrois. It is in this period that Paris’ growth really began.

Spreading over Hollowed Ground

Though we know of Paris’ rapid climb in importance from then, and that we can see portions of its first 1190 mainland fortifications even today, there is no concrete proof of any mining activity before the late thirteenth century. The earliest text we can find is but a mention in the town commerce register: Paris had 18 "quarriers" in 1292. The first written act concerning any mine dates from almost a century later, 1373, in an authorisation that a certain Dame Perrenelle be permitted to operate the plaster mine already existing in her property to the lower flank of Montmartre.

Paris continued to grow in its Right Bank only, leaving the Left bank to schools, abbeys and monasteries. Paris’ walls were rebuilt twice between then and the 16th century but left the Left bank unchanged with its unchanged 13th-century limits marked by its crumbling 13th-century towered fortifications. This Left Bank stagnation probably pleased local miners to no end, as Paris’ most accessible stone was there. Mining activity was so active outside the walls that those closest to the city were already exhausted. Before it became the Chartreuse Coventry from 1259, the land occupied by today’s Luxembourg gardens was that of a certain delapidated Chateau Vauvert. Abandoned since centuries, its land was pockmarked with the wells and cave entries of stone miners, and with the castle itself falling into ruin, the terrain surrounding must have had a sinister look about it. (When even the mines were abandoned brigands and outlaws found refuge there; it was probably their fires and emanating smoke that gave the castle the reputation of being haunted with devils. The expression “Va au diable Vauvert” exists even today.)

That isn’t to say the south wasn’t growing. The city gates thoroughfares had given birth to new centres of population to their outside; in this way appeared the faubourg Saint-Victor (from the eastern extremity of the rue des Écoles and south down the rue Geoffroy St Hilaire), the faubourg St Marcel (rue Descartes, rue Mouffetard) and the faubourg Saint-Jacques (along today’s rue Saint-Jacques below the rue Soufflot). One final agglomeration, born more from the Abbey than from the road to it, was the faubourg (then bourg) Saint-Germain-des-Prés below today’s church of the same name.

History has preserved many records about mines appearing after the 16th century. There were stone excavations operating around today's Jardin des Plantes, Boulevard St-Marcel, Val-de-Grâce hospital, southern Luxembourg (by then the Chartreux Coventry) and in areas around the rue Vaugirard. The plaster mines, for the most part in the southern flank of Montmartre but appearing also to the east, were in full production, especially after it became law (in 1667) that all of Paris’ wood-frame houses be completely covered in the substance to avoid a propagation of fire.

We know a little more today about the Left Bank’s 17th century state then builders did then. François Mansard, hired by Anne d’Autriche to build the Val de Grace church and Coventry from 1645, “discovered” immense caverns under the proposed building site that had bee created more than a century and a half before. The entirety of the building project’s budget would be sunk (literally) into the masonry needed to reinforce the ground below the Coventry foundations. The same sort of discovery was made in 1672 by Claude Perrault, the architect under Louis XIV for the building of l’Observatoire just to the south of there.

Cracks and Crevices

The Crown’s foremost concerns for France’s mines were for the taxes they levied on their product. The first legislation for aboveground safety dated from 1600, but it concerned only Paris itself (the Left Bank had still its 13th century limits). The first general interdiction against mining under any major roadway or public buildings (fountains, monuments, etc) appeared in 1633, a list of forbidden practices that over the next century would grow in length and be increasingly enforced. Unfortunately all these laws concerned only newly opened mines, as the actual extent to which the ground under Paris had been mined was still largely a mystery then.

By the onset of the 18th century Paris had began to grow south around the above monuments, as it was towards the flanks of Montmartre and Belleville. The city’s official limits had expanded twice since the construction of its last late-16th century fortifications (“les fossés jaunes”), and it would be walled anew from 1784 far to its outskirts. This last wall was a tax wall, which provoked new growth of tax-evading entertainment establishments (as wine was dear in Paris) and industries (as combustibles were too). Paris annexed its former faubourgs, and new ones began further along the arteries leaving the wall’s many gates. Appearing directly over areas mined centuries before was growth along today’s avenue de Gobelins (then “route de Fontainebleau”), rue de la Tombe-Issoire, Av Gal. Leclerc (“route de Bourg-la-Reine”) and rue de Vaugirard (past today’s Boulevard Pasteur), and this time on the right Bank, on the higher reaches of the rue de Menilmontant, rue de Belleville and around the lower slopes of Montmartre.

A 1741 report on cracks and sinking in portions of the Bourg-la-Reine roadway seems to have been the first cry of alarm. Even more legislation was passed that year, and again in 1754 it was not only forbidden to open new mines near roadways, but to close exhausted exploitations before they could be inspected. The Crown ordered the same year that that the entire Parisian basin be explored for cavities and maps made of all found, but this order wouldn’t even begin to be executed until 1772. The discoveries made were alarming, but by then it was already too late.

Catastrophes & Reorganisation

Under the weight of Paris’ expanding faubourgs, the first cave-ins occurred from 1774 to the south of Paris’ barrière d’Enfer (today’s place Denfert-Rochereau). The worst of these occurred on the 24th of April 1777, the day of the creation of Paris’ first official mine inspection organisation (“l’Inspection Générale des Carrières” - we may speak of this in another chapter): a house on the rue d’Enfer (boulevard St-Michel today) near the Luxembourg gardens had fallen twenty metres into the mines below. Later the same year, the Right Bank’s ancient plaster mines began to give way as well, with fissures discovered on a roadway in the heights of Menilmontant resulting in reparations to the fontis developing underneath. Circumstances would have it that reparations to the impending cave-in were hastily done by those outside the mine service, and it was in exactly the same spot one year later that the street gave in under the feet of seven promenaders, carrying them among rubble to their death on the mine floor below.

This disaster would result in a rapid re-organisation of Paris’ mine legislation around the sole authority of the Inspection Générale des Carrières. Already begun one year earlier, from then its work could progress unhindered under its head architect, Charles-Axel Guillaumot. The consolidation of Paris’ streets was no simple affair, and we will look at it in more detail in our next chapter.