Around 122 CE, the Roman emperor Hadrian ordered a wall built right across the narrowest part of Britain. It stretched 73 miles from coast to coast, marking the northern edge of the Roman Empire. To the north lay tribes the Romans never managed to conquer.
The wall took about six years to finish and stood up to 20 feet tall in places, with deep ditches in front of it. Soldiers lived in forts spaced along its length, watching for raids. Around 10,000 troops were stationed there at any time - soldiers from places like Syria, Spain and Germany, all stuck in cold, rainy northern Britain.
We even know what those soldiers complained about. At a fort called Vindolanda, archaeologists found wooden tablets with personal letters preserved in the wet soil. One soldier asked his family back home to send warm socks and underwear. Some grumbles never change.
