Rome was founded in 753 BC by the twins Romulus and Remus. The Roman Empire was founded in 27 BC and Augustus Caesar proclaimed himself emperor of Rome in 31 BC. After the Roman Empire broke down in 395 AD, there were many separate kingdoms and city states. Italy became one nation only in 1861. Since then the country also includes the islands of Sicily and Sardegna. The 'Kingdom of Italy' lasted from 1861 until 1946. During the Second World War, Italy's Prime Minister Benito Mussolini sided with the German Nazi regime. The Italian Republic was formed in 1946.