Boulogne-sur-Mer

Boulogne-sur-Mer (French: [bulɔɲ syʁ mɛʁ] ^ⓘ; Picard: Boulonne-su-Mér; Dutch: Bonen; Latin: Gesoriacum or Bononia), often called just Boulogne (UK: /bʊˈlɔɪn/, US: /buːˈloʊn, buːˈlɔɪn/), is a coastal city in Northern France. It is a sub-prefecture of the department of Pas-de-Calais. Boulogne lies on the Côte d'Opale, a touristic stretch of French coast on the English Channel between Calais and Normandy, and the most visited location in the region after the Lille conurbation. Boulogne is its department's second-largest city after Calais, and the 183rd-largest in France. It is also the country's largest fishing port, specialising in herring.

Boulogne is an ancient town and was the main Roman port for trade and communication with its Province of Britain. After a period of Germanic presence following the collapse of the Empire, Boulogne was integrated into the County of Boulogne of the Kingdom of France during the Middle Ages. It was occupied by the Kingdom of England numerous times due to conflict between the two nations. In 1805 it was a staging area for Napoleon's troops for several months during his planned invasion of the United Kingdom.

The city's 12th-century belfry is recognised by UNESCO as a World Heritage Site (along with other belfries of Belgium and France), while another popular attraction is the marine conservation centre Nausicaa.

The French name Boulogne derives from the Latin Bononia, which was also the Roman name for Bologna in Italy. Both places – and Vindobona (Vienna) – are thought to have derived from native Celtic placenames, with bona possibly meaning "foundation", "citadel", or "granary".^{[citation needed]} The French epithet sur-Mer ("on sea") distinguishes the city from Boulogne-Billancourt on the edge of Paris. In turn, the Boulogne in Boulogne-Billancourt originates from a church there dedicated to Notre-Dame de Boulogne, "Our Lady of Boulogne[-sur-Mer]".

The foundation of the city known to the Romans as Gesoriacum is credited to the Celtic Boii. In the past, it was sometimes conflated with Caesar's Portus Itius, but that is now thought to have been a site near Calais which has since silted up. A tall lighthouse was built at Gesoriacum circa 39 AD by order of the Emperor Caligula, possibly in preparation for an invasion of Britain. Known as the Tour d'Ordre, coastal erosion caused it to topple into the sea in 1644.

From the time of Claudius's invasion in AD 43, Gesoriacum formed the major port connecting the rest of the empire to Britain. It was the chief base of the Roman navy's Britannic fleet until the rebellion of its admiral Carausius in 286. As part of the imperial response, the junior emperor Constantius Chlorus successfully besieged it by land and sea in 293. The name of the settlement was changed to Bononia at some point between the sack of Gesoriacum and 310, possibly as a consequence of its refounding or possibly by the replacement of the sacked and lower-lying city by another nearby community.

The city was an important town of the Morini (the 'sea people'), and Zosimus called it Germanorum ("Germanic-speaking") at the end of the 4th century.

In the Middle Ages Boulogne was the capital of an eponymous county, founded in the mid-9th century. An important Count, Eustace II, assisted William the Conqueror in his conquest of England. His wife founded the city's Notre Dame cathedral, which became a site of pilgrimage from the 12th century onwards, attended by fourteen French kings and five of England. It was an important whaling center prior to 1121. The city survived on herring fishing and received its municipal charter from Count Renaud of Dammartin in 1203.