The city of Saint Louis was founded in 1765 by the French Pierre Laclede, it takes its name from King Louis IX, referenced by historians as the king of the crusades. A century later, the city became the gateway to the west for pioneers, trappers and other adventurous explorers. Saint Louis is a city with a particular geographical situation, which places it for multiple reasons at a crossroads. It marks the border between the states of Illinois and Missouri (Saint Louis is located in Missouri, East Saint Louis in Illinois), it is north of the city that the Missouri River flows into the Mississippi River and it is also in Saint Louis that two mythical roads cross: Highway 61 and Highway 66. Besides the fact that it is reputed to be the gate of the west, Saint Louis is for some the last city of the south, for others, it is the first city of the north! Anyway, Saint Louis is today a city of 320 000 inhabitants (agglomeration of 2,5 million inhabitants), which makes it the most populated city of the Mississippi valley. Saint Louis must have known its hour of glory at the beginning of the 20th century. According to the 1900 census, Saint-Louis is the fourth most populous city in the United States. At the time, large industrial center (Ralston-Purina, Anheuser-Busch, International Shoe and Brown Shoe Company), the city organized the summer Olympic Games in 1904 (the 3rd of the modern era). Saint Louis hosted the 1904 Louisiana Purchase Exposition / St. Louis World's Fair in Forest Park, west of downtown, of which only one pavilion remains. During the second half of the 20th century, the city experienced a significant and steady decline linked to deindustrialisation. During this period, the city's population was halved. downtown According to the 2010 census, Saint-Louis is only the 58th most populous city in the United States, which means that there is space, few traffic and parking problems. Since 2000, enormous efforts have been made to revitalize Saint Louis (restoration of historic buildings such as the Fox theater, renovation of districts such as Soulard, creation of parks such as the city garden and numerous museums, organization of festivals of all kinds, destruction of unhealthy buildings, construction of a new bridge over the Mississippi etc...). In particular, downtown Saint-Louis has experienced a spectacular renaissance. Lofts and apartments have been converted into old warehouses and industrial buildings, dozens of new businesses have opened, and the population is growing again. If Saint Louis is not yet considered as a tourist city (at least seen from France) and that it is always considered as dangerous, the city knew to rebound, it became really interesting to visit. It could even soon become a tourist mecca in the USA because it has many riches to discover. The work carried out in 2014 to link the arch gateway and its park to the city centre (a green area will cover the motorway) will only accelerate the movement.