orecastCologne, the Hohe Straße. Every day tens of thousands push through this shopping street — and hardly anyone knows they are all walking on a road that ran exactly here two thousand years ago. To this day the Hohe Straße follows the Cardo Maximus, the main axis of the Roman city. The Romans called it Colonia Claudia Ara Agrippinensium; its people simply said the Colonia. Our city episode descends into this Cologne beneath Cologne.
A city on the water
It all began at the Rhine. Where the Heumarkt lies today, there was then an island in the river, and behind it the city's sheltered harbour — a street there is still called Am Alten Ufer, at the old bank. The city behind it was a fortress: a wall eight metres high with nineteen towers. One of them still stands in the middle of the city, the Römerturm on Zeughausstraße. Where the Cardo and the Decumanus crossed — today the corner of Hohe Straße and Schildergasse — beat the heart of the Colonia, and right beside it lay the forum: market, court and stage in one.
Cologne glass and Eifel water
In the workshops outside the gates arose Cologne's most famous export: glass, blown so skilfully that it was sold as far as Rome. Roman glass from Cologne lies today in museums around the world. And the Colonia afforded itself a luxury that still astonishes: spring water from the Eifel, through a channel of nearly a hundred kilometres, past places now called Hürth or Brühl. The water flowed into fountains, houses and the baths, where the city met to bathe, talk and do business — the bathhouses were the Colonia's living room. In the evening people sat in the taverns along the Cardo over wine and dice, while oil lamps burned in the lanes.
How a city vanished into the ground
Then, over centuries, this world sank away. The empire fell apart, new houses grew over the old, and the Colonia disappeared into the ground, layer upon layer. Yet it is still there. Directly beneath the city hall lies the Praetorium, the palace of the Roman governor; its walls still stand in the dark, a few metres below the Alter Markt. Beside the cathedral, on Roncalliplatz, a bunker dig struck the Dionysus mosaic — over a million tesserae, the floor of a dining room, almost intact and still exactly where it was laid. And beneath the Kleine Budengasse the Roman sewer still runs, a tunnel you can walk through upright, built by hands two thousand years ago.
A morning in the Colonia
Picture a morning on the Cardo Maximus, today's Hohe Straße. Traders open their shops, the air smells of fresh bread, carts rumble over the paving — a shopping street even then. Between the colonnades crowded people from across the empire: officials and legionaries, traders from Gaul and the East, craftsmen, slaves and children. The Colonia was no distant provincial settlement but one of the most important cities north of the Alps, with running water, heated baths and a harbour that brought goods from half the Mediterranean to the Rhine.
Anyone who stepped through its gates entered a piece of Rome, in the middle of Germania. On the forum people bargained and justice was pronounced, in the baths people bathed and talked, in the workshops outside the wall the famous Cologne glass was made. In the evening the oil lamps burned and dice rattled in the taverns. It was a loud, living city — not a ruin, but a place where people went about their business, celebrated and quarrelled just as today. It is exactly this everyday life that makes the Colonia so tangible: the bread, the wine, the glass, the water from the Eifel. Much of it lies today just a few metres below the asphalt over which the tram rolls — a complete urban day, preserved in the ground, right beneath the feet of the people hurrying to work along the same street each morning. And so a shopping trip suddenly becomes a journey through time.
Two cities, one above the other
Anyone walking the Hohe Straße today walks through two cities at once: one above, one below in the dark, separated only by a few metres of earth. Most of the Colonia has never been excavated. Beneath department stores, pubs and car parks it simply lies there and waits. The Roman city has not vanished — it just lies deeper than we think, beneath the pavement and beneath the names of the streets. That is exactly what orecast makes visible: on the map you can see which historical layers and documented finds lie beneath a place, from open, checked sources such as OpenStreetMap and Wikidata, honestly and with no invented points. Above, the Cologne of today; below, the Colonia — and in between two thousand years and a few metres of earth. Watch the episode, then take a look at the map of your own street.