There was a saying in medieval Germany: Stadtluft macht frei. City air makes you free. The rule, in many places, was that a serf who escaped to the city and lived there for a year and a day would become a free person. This is the kind of legal weirdness the Middle Ages were full of. Cities had largely freed themselves from the feudal system that bound peasants to the land, and a runaway serf who could survive a year in the close, plague-prone, often deadly streets of a medieval town came out with citizenship. The cities needed the labor. Most of them could not maintain their populations through birth rates alone, given how lethal urban life was, so they relied on continuous immigration from the countryside. The bargain was harsh, but it was a bargain. For many people, it was the first one the law had ever offered them.

Old Germanic law had a concept called were-gild, sometimes translated as man-money. If you killed someone, you could pay their next of kin a fixed sum as restitution, and that, formally, was the end of it. To modern sensibilities this looks scandalously cheap. To the people who created it, it was a circuit breaker. Endless cycles of revenge killing, family against family for generations, were the real danger to a small society, and a price tag on a life was a way to stop the spiral. The principle never quite disappeared. Anglo-Saxon law still recognizes wrongful death torts, which are essentially were-gild dressed up in modern lawyer's clothing. The Spanish Inquisition, that famous engine of cruelty, actually set the standard of proof for witchcraft accusations so high that almost no case could meet it. Posterity has flattened the medieval legal system into torture chambers and iron maidens. The truth was messier and, in many places, more interesting.

By the High Middle Ages, almost every town and city in Europe had walls. Their daily job was usually not defense but toll collection. You wanted to enter the city to sell goods, you paid at the gate. Castles and walls became militarily obsolete as gunpowder weapons improved, and most walls were torn down as cities grew, the stone scavenged for new buildings or, by the nineteenth century, cleared away to make room for railways. But not all of them. Look at almost any old European city today and you will see the ghost of its medieval walls in a circular street ringing the old town, sometimes still called something like Ringstrasse or Boulevard Circulaire. Where the moats survived, they have become green parks or canals threading through the city center. The walls themselves became archaeology that you walk past on the way to lunch.

Much of what survives from medieval rural Europe is wooden, because wood was what was available. The half-timbered houses that used to define the old towns of central Europe, before twentieth-century firebombing took out so many of them, were built from a wooden skeleton filled with mud, dung, and whatever came to hand. This material choice has turned out to be a gift to archaeology. The science of dendrochronology can date a tree by the sequence of its growth rings, and in Europe the technique can produce absolute datings, accurate to the year the tree was cut down, well into the medieval period. We know when individual beams in individual houses were felled. The medieval food in those houses, by the way, was missing things you would consider essential. No potatoes, no tomatoes, no zucchini, no corn. Turnips and leeks were what root vegetables meant. Barley, oats, and rye were the everyday grains; wheat was a luxury. Salt was a strategic commodity, because pickling and salting were the way most food was preserved. The Middle Ages tasted very different from what came after the Americas joined the world.