Two millennia ago, the Roman Empire reached the limits of its power in Britain. The island marked the northernmost border of the Roman Empire and the point at which the ancient superpower's expansion came to a halt.
The Romans launched several invasions and kept 10% of the entire army in the province but failed to conquer the whole island. Instead, a militarized frontier divided the island in two — marked by the 73-mile-long (118 kilometers) Hadrian's Wall, which was the border for nearly 300 years.
