Not least among the earlier tombs in Saint-Denis is that of Charles Martel, the Frankish leader who a century after the death of Mohammed, when the Umayyad Caliphate was pushing relentlessly into Europe, forced the Muslim armies back. Martel’s victory at the Battle of Tours in 732 is recognised for having prevented the spread of Islam throughout Europe. Had his Frankish armies not succeeded no other power in Europe could have stopped the Muslim armies from conquering the continent. When those armies had crossed into Europe in 711 one of their leaders, Tariq bin Zayad, famously ordered their boats to be burnt, saying ‘We have not come here to return. Either we conquer and establish ourselves, or we perish.’ Martel ensured that they perished and that other than having gained a foothold in southern Spain, Islam would never progress further into Europe. As Edward Gibbon famously wrote a millennium later, were it not for the victory of the man who became known as ‘The Hammer’: ‘Perhaps the interpretation of the Koran would now be taught in the schools of Oxford, and her pulpits might demonstrate to a circumcised people the sanctity and truth of the revelation of Mohammed.’ As Gibbon went on, ‘From such calamities was Christendom delivered by the genius and fortune of one man.’12

Today a visitor to the basilica in which Martel’s tomb sits may well wonder whether he did indeed succeed – or at least reflect that after he succeeded his descendants failed. To wander the district of Saint-Denis today is to see a district more resembling North Africa than France. The market square outside the basilica is a souk more than a market. Stalls sell different styles of hijab and radical groups hand out literature against the state. Inside, though all the clergy are elderly white men the residual congregation is black African, part of the non-Muslim wave of immigration into the area from Martinique and Guadeloupe.

This area has one of the highest Muslim populations in France. Around 30 per cent of the population of Seine Saint-Denis, also known as the 93rd district, are Muslim. No more than 15 per cent are Catholic. But with most of the immigrants in the area from the Maghreb and sub-Saharan Africa and a growing youth population, it is not surprising that even in the district’s private Catholic schools around 70 per cent of the students are Muslim. Meanwhile the area’s Jewish population has halved in recent years. According to the Interior Ministry the district has around 10 per cent (230) of the total number of known mosques in France. If you visit them you can see that there are nowhere near enough for the needs of the community. At Friday prayers worshipers spill out onto the streets and a number of the major mosques are struggling to create larger facilities to meet the demand.