The earliest settlements were built here, followed by the small Gallic town of Lutetia, overrun by Julius Caesar’s troops in 52 BC. A natural defensive site commanding a major east–west river trade route, it was an obvious candidate for a bright future. In 508 it became the stronghold of the Merovingian kings, then of the counts of Paris, who in 987 became kings of France.
The Frankish kings built themselves a splendid palace at the western tip of the island, of which the Sainte-Chapelle and Conciergerie survive today. At the other end of the island, they erected the great cathedral of Notre-Dame. By the early thirteenth century this tiny island had become the bustling heart of the capital, though it’s hard to imagine this today: virtually the whole medieval city was erased by Baron Haussmann in the nineteenth-century and replaced by four imposing Neoclassical edifices, including the Palais de Justice.