During its history, Saint-Denis has been closely associated with the French royal house.
Starting from Dagobert I (c. 603–639), almost every French king was buried in the Basilica.

However, Saint-Denis is older than that.
In the 2nd century, there was a Gallo-Roman village named Catolacus on the location that Saint-Denis occupies today.
Saint Denis, the first bishop of Paris and patron saint of France, was martyred in about 250 AD and buried in the cemetery of Catolacus.
Denis' tomb quickly became a place of worship.
Around 475 AD, Sainte Geneviève had a small chapel erected on Denis' tomb, which by then had become a popular destination for pilgrims.
It was this chapel that Dagobert I had rebuilt and turned into a royal monastery.
Dagobert granted many privileges to the monastery: independence from the bishop of Paris, the right to hold a market, and, most importantly, he was buried in Saint-Denis; a tradition which was followed by almost all his successors.
During the Middle Ages, because of the privileges granted by Dagobert, Saint-Denis grew to become very important.
Merchants from all over Europe (and indeed from the Byzantine Empire) came to visit its market.

In 1140, Abbot Suger, counselor to the King, granted further privileges to the citizens of Saint-Denis.
He also started the work of enlarging the Basilica of Saint Denis that still exists today, often cited as the first example of high early Gothic Architecture.
The new church was consecrated in 1144.

Saint-Denis was depopulated in the Hundred Years' War; of its 10,000 citizens, only 3,000 remained after the war.

During the French Wars of Religion, the Battle of Saint-Denis was fought between Catholics and Protestants on 10 November 1567.
The Protestants were defeated, but the Catholic commander Anne de Montmorency was killed.
In 1590, the city surrendered to Henry IV, who converted to Catholicism in 1593 in the abbey of Saint-Denis.

King Louis XIV (1638–1715) started several industries in Saint-Denis: weaving and spinning mills and dyehouses.
His successor, Louis XV (1710–1774), whose daughter was a nun in the Carmelite convent, took a lively interest in the city: he added a chapel to the convent and also renovated the buildings of the royal abbey.

During the French Revolution, not only was the city renamed "Franciade" from 1793 to 1803, but the royal necropolis was looted and destroyed.
The remains were removed from the tombs and thrown together; during the French Restoration, since they could not be sorted out anymore, they were reburied in a common ossuary.

The last king to be interred in Saint-Denis was Louis XVIII (1755 – 1824).
After France became a republic and an empire, Saint-Denis lost its association with royalty.

On 1 January 1860, the city of Paris was enlarged by annexing neighbouring communes.
On that occasion, the commune of La Chapelle-Saint-Denis was disbanded and divided between the city of Paris, Saint-Denis, Saint-Ouen, and Aubervilliers.
Saint-Denis received the north-western part of La Chapelle-Saint-Denis.

During the 19th century, Saint-Denis became increasingly industrialised.
Transport was much improved: in 1824 the Canal Saint-Denis was constructed, linking the Canal de l'Ourcq in the northeast of Paris to the River Seine at the level of L'Île-Saint-Denis, and in 1843 the first railway reached Saint-Denis.
By the end of the century, there were 80 factories in Saint-Denis.

The presence of so many industries also gave rise to an important socialist movement.
In 1892, Saint-Denis elected its first socialist administration, and by the 1920s, the city had acquired the nickname of la ville rouge, the red city.
Until Jacques Doriot in 1934, all mayors of Saint-Denis were members of the Communist Party.

During the Second World War, after the defeat of France, Saint-Denis was occupied by the Germans on 13 June 1940.
There were several acts of sabotage and strikes, most notably on 14 April 1942 at the Hotchkiss factory.
After an insurgency which started on 18 August 1944, Saint-Denis was liberated by the 2nd Armored Division (France) on 27 Aug
During its history, Saint-Denis has been closely associated with the French royal house. Starting from Dagobert I (c. 603–639), almost every French king was buried in the Basilica.
However, Saint-Denis is older than that. In the 2nd century, there was a Gallo-Roman village named Catolacus on the location that Saint-Denis occupies today. Saint Denis, the first bishop of Paris and patron saint of France, was martyred in about 250 AD and buried in the cemetery of Catolacus. Denis' tomb quickly became a place of worship. Around 475 AD, Sainte Geneviève had a small chapel erected on Denis' tomb, which by then had become a popular destination for pilgrims. It was this chapel that Dagobert I had rebuilt and turned into a royal monastery. Dagobert granted many privileges to the monastery: independence from the bishop of Paris, the right to hold a market, and, most importantly, he was buried in Saint-Denis; a tradition which was followed by almost all his successors. During the Middle Ages, because of the privileges granted by Dagobert, Saint-Denis grew to become very important. Merchants from all over Europe (and indeed from the Byzantine Empire) came to visit its market.
In 1140, Abbot Suger, counselor to the King, granted further privileges to the citizens of Saint-Denis. He also started the work of enlarging the Basilica of Saint Denis that still exists today, often cited as the first example of high early Gothic Architecture. The new church was consecrated in 1144.
Saint-Denis was depopulated in the Hundred Years' War; of its 10,000 citizens, only 3,000 remained after the war.
During the French Wars of Religion, the Battle of Saint-Denis was fought between Catholics and Protestants on 10 November 1567. The Protestants were defeated, but the Catholic commander Anne de Montmorency was killed. In 1590, the city surrendered to Henry IV, who converted to Catholicism in 1593 in the abbey of Saint-Denis.
King Louis XIV (1638–1715) started several industries in Saint-Denis: weaving and spinning mills and dyehouses. His successor, Louis XV (1710–1774), whose daughter was a nun in the Carmelite convent, took a lively interest in the city: he added a chapel to the convent and also renovated the buildings of the royal abbey.
During the French Revolution, not only was the city renamed "Franciade" from 1793 to 1803, but the royal necropolis was looted and destroyed. The remains were removed from the tombs and thrown together; during the French Restoration, since they could not be sorted out anymore, they were reburied in a common ossuary.
The last king to be interred in Saint-Denis was Louis XVIII (1755 – 1824). After France became a republic and an empire, Saint-Denis lost its association with royalty.
On 1 January 1860, the city of Paris was enlarged by annexing neighbouring communes. On that occasion, the commune of La Chapelle-Saint-Denis was disbanded and divided between the city of Paris, Saint-Denis, Saint-Ouen, and Aubervilliers. Saint-Denis received the north-western part of La Chapelle-Saint-Denis.
During the 19th century, Saint-Denis became increasingly industrialised. Transport was much improved: in 1824 the Canal Saint-Denis was constructed, linking the Canal de l'Ourcq in the northeast of Paris to the River Seine at the level of L'Île-Saint-Denis, and in 1843 the first railway reached Saint-Denis. By the end of the century, there were 80 factories in Saint-Denis.
The presence of so many industries also gave rise to an important socialist movement. In 1892, Saint-Denis elected its first socialist administration, and by the 1920s, the city had acquired the nickname of la ville rouge, the red city. Until Jacques Doriot in 1934, all mayors of Saint-Denis were members of the Communist Party.
During the Second World War, after the defeat of France, Saint-Denis was occupied by the Germans on 13 June 1940. There were several acts of sabotage and strikes, most notably on 14 April 1942 at the Hotchkiss factory. After an insurgency which started on 18 August 1944, Saint-Denis was liberated by the 2nd Armored Division (France) on 27 Aug
Saint-Denis, Seine-Saint-Denis