This tribe was one of sixty-four which were confederated, and when the conquest of Gaul took place under Julius Caesar, the Parisii occupied the island. The ground now covered by Paris was either a marsh or forest, and two bridges communicated from the island to it. The islanders were slow to give up their Druidical sacrifices, and it is doubtful whether the Roman gods ever were worshiped by them, though fragments of an altar of Jupiter have been found under the choir of the cathedral of Notre Dame. Nearly four hundred years after Christ, the Emperor Julian remodeled the government and laws of Gaul and Lutetia, and changed its name to Parisii. It then, too, became a city, and had considerable trade. For five hundred years Paris was under Roman domination. A palace was erected for municipal purposes in the city, and another on the south bank of the Seine, the remains of which can still be seen. The Roman emperors frequently resided in this palace while waging war with the northern barbarians. Constantine and Constantius visited it; Julian spent three winters in it; Valentian and Gratian also made it a temporary residence.
The monks have a tradition that the gospel was first preached in Paris about the year 250, by St. Denis, and that he suffered martyrdom at Montmartre. A chapel was early erected on the spot now occupied by Notre Dame. In 406 the northern barbarians made a descent upon the Roman provinces, and in 445 Paris was stormed by them. Before the year 500 Paris was independent of the Roman domination. Clovis was its master, and marrying Clotilde, he embraced Christianity and erected a church. The island was now surrounded by walls and had gates. The famous church of St. German L’Auxerrois was built at this time. For two hundred and fifty years, Paris retrograded rather than advanced in civilization, and the refinements introduced by the Romans were nearly forgotten. In 845 the Normans sacked and burnt Paris. Still again it was besieged, but such was the valor of its inhabitants that the enemy were glad to raise the siege. Hugues Capet was elected king in 987, and the crown became hereditary. In his reign the Palace of Justice was commenced. Buildings were erected on all sides, and new streets were opened. Under Louis le Gros the Louvre was rebuilt, it having existed since the time of Dagobert. Bishop Sully began the foundations of Notre Dame in 1163, and about that time the Knights Templars erected a palace.
Under the reign of Philip Augustus many of the public edifices were embellished and new churches and towers were built. In 1250 Robert Serbon founded schools—a hospital and school of surgery were also about this time commenced.