The founding of Rome is shrouded in legend, but current archaeological evidence supports the theory that Rome grew from pastoral settlements and coalesced into a city in the 8th century BC. It developed into the capital of the Roman Kingdom, the Roman Republic, and finally the Roman Empire. This success depended on military conquest and commercial predominance. Rome expanded over most of Europe and the shores of the Mediterranean sea. For almost a thousand years, Rome was the most politically important, richest and largest city in the Western world, and remained so after the Empire started to decline and was split. With the rise of early Christianity, the Bishop of Rome gained religious as well as political importance, eventually becoming known as the Pope and establishing Rome as the centre of the Catholic Church. Rome remained the capital of the Papal States until its annexation into the kingdom of Italy in 1870. Caught up in the nationalistic turmoils of the 19th century, Rome became the focus of the hopes for Italian unification, it was declared capital in 1871. After a victorious First World War, Rome witnessed the rise to power of Italian fascism guided by Benito Mussolini, who marched on the city in 1922, eventually declared a new Empire and allied Italy with Nazi Germany. After his execution and the end of the war, Rome grew momentously, as one of the driving forces behind the Italian economic miracle of post-war reconstruction. When it became a fashionable city in the 1950s and early 1960s, the years of 'la Dolce Vita, the magnificent city had acquired yet another identity.