Paris was founded on an island, currently known as Île de la Cité, of the River Seine in the 3rd century BC by a Celtic tribe known as the Parisii. The Romans, under Julius Caesar, took the city in 52 BC and called it Lutetia, expanding the city on the Left Bank. In 508 the Frankish king Clovis I made the city his capital. The city expanded on the Right Bank in the 11th century, and in the 12th and 13th centuries buildings like the cathedral of Notre Dame and the Sainte Chapelle were built. In the 19th century urban reconstruction, with wide squares and boulevards, were undertaken by Haussmann, which changed the character of Paris into a modern urban city.