Acre has existed for at least 4,500 years, but reached the height of its importance with the Crusader conquest in 1104.Under Christian rule, the city became an unruly trading hub home to combative orders of soldier-monks, European factions that distrusted each other and sometimes fought in the streets, competing merchants from cities like Genoa, Venice and Pisa, and small populations of Jews and Muslims, all sharing an enclosed area that at its height was barely the size of two football fields.