There was an official end to the Roman Empire, a conclusion on a specific date. September 4, 476. It was a Monday. Romulus Augustulus, the child Emperor, surrendered to Flavius Odoacer, a military leader of East Germanic descent, who became king of Italy.
We know it was Monday because by then the Romans had named the days of the week, and months of the year, in a way we continue to recognise. They shaped our world, and still do. Public toilets, locks and keys, indoor plumbing, fast-drying cement, socks, post, apartments, shoes, satire, the magnifying glass, all were either created or improved beyond recognition by the Romans.